Quote from superdav42 on May 27, 2025, 03:11

As others have mentioned the release of WooCommerce Subscriptions 7.5 broke our site. The guide for making compatibility changes in WCS is also out-of-date since many of the files have changed locations from vendor to includes/core. It's also very bad practice to update other plugins code directly as it is error-prone and required every time the plugin is updated. I looked through the WCS code and identified filters that can be used instead of making direct code changes. I packaged it up all in a class that anyone could drop into a snippet to get their site working but I suggest it be integrated into Fox - Currency Switcher in the next version.

<?php
/**
 * Plugin Name:  Fix FOX multicurrency with Woocommerece Subscriptions.
 * Description:  Fix CSS
 * Version:      1.0.0
 * Author:       Dave
 * License:      MIT License
 */

/**
 * Class WOOCS_Subscription_Fix
 * Handles WooCommerce Currency Switcher (WOOCS) fixes for WooCommerce Subscriptions
 */
class WOOCS_Subscriptions_Compatibility {
    
    /**
     * Initialize the filters
     */
    public function init() {

       // Subscription price string details
       add_filter('woocommerce_subscription_price_string_details',
          [$this, 'fix_subscription_price_string_details'], 100, 2);

       // Get subscription orders
       add_filter('wcs_get_subscription_orders',
          [$this, 'fix_subscription_orders'], 10, 3);

       // New order items
       add_filter('wcs_new_order_items',
          [$this, 'fix_new_order_items'], 2, 3);

       // Variable subscription price HTML
       add_filter('woocommerce_variable_subscription_price_html',
          [$this, 'fix_variable_subscription_price_html'], 10, 2);

       // Subscription product price string
       add_filter('woocommerce_subscriptions_product_price_string',
          [$this, 'fix_subscription_product_price_string'], 10, 3);

       // Subscription product price
       add_filter('woocommerce_subscriptions_product_price',
          [$this, 'fix_subscription_product_price'], 10, 2);

       // Renewal product title
       add_filter('woocommerce_subscriptions_renewal_product_title',
          [$this, 'fix_renewal_product_title'], 10, 2);

       // Cart item from session
       remove_filter('woocommerce_get_cart_item_from_session',
          [WC_Subscriptions_Core_Plugin::instance()->get_cart_handler(WCS_Cart_Renewal::class), 'add_cart_item_data']);
       add_filter('woocommerce_get_cart_item_from_session',
          [$this, 'adjust_cart_item_price_from_session'], 12, 3);
    }

    public function fix_subscription_price_string_details() {
       global $WOOCS;

       $order_currency = $subscription->get_meta('_order_currency');
       if ($order_currency && $WOOCS->current_currency !== $order_currency) {
          $WOOCS->set_currency($order_currency);
       }
       return $arg;
    }
    public function fix_subscription_orders ( $orders, $return_fields, $order_type) {

       if ( 'all' === $return_fields ) {
          foreach ( $orders as $order ) {
             global $WOOCS;
             $order_currency = $order->get_meta('_order_currency');
             if ($order_currency && $WOOCS->current_currency != $order_currency) {
                $WOOCS->set_currency($order_currency);
             }
          }
       }
       return $orders;
    }
    public function fix_new_order_items($items, $new_order, $subscription ) {
       global $WOOCS;
       $order_currency = $subscription->get_meta('_order_currency');
       if ($order_currency && $WOOCS->current_currency != $order_currency) {
          $WOOCS->set_currency($order_currency);
       }
       return $items;
    }

    public function fix_variable_subscription_price_html( $price, $product ) {
       $prices                 = $product->get_variation_prices( true );
       $min_price_variation_id = $product->get_meta( '_min_price_variation_id' );

       $tax_display_mode = get_option( 'woocommerce_tax_display_shop' );

       $price = \WC_Subscriptions_Product::get_price( $min_price_variation_id );
       if (isset($prices['price'][$min_price_variation_id])) {
          $price = $prices['price'][$min_price_variation_id];
       }
       $price = 'incl' == $tax_display_mode ? wcs_get_price_including_tax( $product, array( 'price' => $price ) ) : wcs_get_price_excluding_tax( $product, array( 'price' => $price ) );
       $price = $product->get_price_prefix( $prices ) . wc_price( $price ) . $product->get_price_suffix();
       $price = apply_filters( 'woocommerce_variable_price_html', $price, $product );
       $price = \WC_Subscriptions_Product::get_price_string( $product, array( 'price' => $price ) );

       return $price;
    }
    public function fix_subscription_product_price_string($subscription_string, $product, $include ) {
       global $wp_locale;

       if ( ! \WC_Subscriptions_Product::is_subscription( $product ) ) {
          return;
       }

       $base_price          = \WC_Subscriptions_Product::get_price( $product );
       $billing_interval    = (int) \WC_Subscriptions_Product::get_interval( $product );
       $billing_period      = \WC_Subscriptions_Product::get_period( $product );
       $subscription_length = (int) \WC_Subscriptions_Product::get_length( $product );
       $trial_length        = (int) \WC_Subscriptions_Product::get_trial_length( $product );
       $trial_period        = \WC_Subscriptions_Product::get_trial_period( $product );
       $sign_up_fee         = 0;
       $include_length      = $include['subscription_length'] && 0 !== $subscription_length;

       if ( empty( $billing_period ) ) {
          $billing_period = 'month';
       }

       if ( $include_length ) {
          $ranges = wcs_get_subscription_ranges( $billing_period );
       }

       if ( $include['sign_up_fee'] ) {
          $sign_up_fee = is_bool( $include['sign_up_fee'] ) ? \WC_Subscriptions_Product::get_sign_up_fee( $product ) : $include['sign_up_fee'];
       }

       if ( $include['tax_calculation'] ) {
          if ( in_array( $include['tax_calculation'], array( 'exclude_tax', 'excl' ), true ) ) {
             // Calculate excluding tax.
             $price = isset( $include['price'] ) ? $include['price'] : wcs_get_price_excluding_tax( $product );
             if ( true === $include['sign_up_fee'] ) {
                $sign_up_fee = wcs_get_price_excluding_tax( $product, array( 'price' => \WC_Subscriptions_Product::get_sign_up_fee( $product ) ) );
             }
          } else {
             // Calculate including tax.
             $price = isset( $include['price'] ) ? $include['price'] : wcs_get_price_including_tax( $product );
             if ( true === $include['sign_up_fee'] ) {
                $sign_up_fee = wcs_get_price_including_tax( $product, array( 'price' => \WC_Subscriptions_Product::get_sign_up_fee( $product ) ) );
             }
          }
       } else {
          $price = isset( $include['price'] ) ? $include['price'] : wc_price( $base_price );
       }

       if ( is_numeric( $sign_up_fee ) ) {
          global $WOOCS;
          if ($WOOCS->is_multiple_allowed) {
             $sign_up_fee = $WOOCS->woocs_exchange_value(floatval($sign_up_fee));
          }
          $sign_up_fee = wc_price( $sign_up_fee );
       }

       $price .= ' <span class="subscription-details">';

       $subscription_string = '';

       if ( $include['subscription_price'] && $include['subscription_period'] ) { // Allow extensions to not show price or billing period e.g. Name Your Price.
          if ( $include_length && $subscription_length === $billing_interval ) {
             $subscription_string = $price; // Only for one billing period so show "$5 for 3 months" instead of "$5 every 3 months for 3 months".
          } elseif ( \WC_Subscriptions_Synchroniser::is_product_synced( $product ) && in_array( $billing_period, array( 'week', 'month', 'year' ), true ) ) {
             $subscription_string = '';

             if ( \WC_Subscriptions_Synchroniser::is_payment_upfront( $product ) && ! \WC_Subscriptions_Synchroniser::is_today( \WC_Subscriptions_Synchroniser::calculate_first_payment_date( $product, 'timestamp' ) ) ) {
                /* translators: %1$s refers to the price. This string is meant to prefix another string below, e.g. "$5 now, and $5 on March 15th each year" */
                $subscription_string = sprintf( __( '%1$s now, and ', 'woocommerce-subscriptions' ), $price );
             }

             $payment_day = \WC_Subscriptions_Synchroniser::get_products_payment_day( $product );
             switch ( $billing_period ) {
                case 'week':
                   $payment_day_of_week = \WC_Subscriptions_Synchroniser::get_weekday( $payment_day );
                   if ( 1 === $billing_interval ) {
                      // translators: 1$: recurring amount string, 2$: day of the week (e.g. "$10 every Wednesday").
                      $subscription_string .= sprintf( __( '%1$s every %2$s', 'woocommerce-subscriptions' ), $price, $payment_day_of_week );
                   } else {
                      $subscription_string .= sprintf(
                      // translators: 1$: recurring amount string, 2$: period, 3$: day of the week (e.g. "$10 every 2nd week on Wednesday").
                         __( '%1$s every %2$s on %3$s', 'woocommerce-subscriptions' ),
                         $price,
                         wcs_get_subscription_period_strings( $billing_interval, $billing_period ),
                         $payment_day_of_week
                      );
                   }
                   break;
                case 'month':
                   if ( 1 === $billing_interval ) {
                      if ( $payment_day > 27 ) {
                         // translators: placeholder is recurring amount.
                         $subscription_string .= sprintf( __( '%s on the last day of each month', 'woocommerce-subscriptions' ), $price );
                      } else {
                         $subscription_string .= sprintf(
                         // translators: 1$: recurring amount, 2$: day of the month (e.g. "23rd") (e.g. "$5 every 23rd of each month").
                            __( '%1$s on the %2$s of each month', 'woocommerce-subscriptions' ),
                            $price,
                            wcs_append_numeral_suffix( $payment_day )
                         );
                      }
                   } else {
                      if ( $payment_day > 27 ) {
                         $subscription_string .= sprintf(
                         // translators: 1$: recurring amount, 2$: interval (e.g. "3rd") (e.g. "$10 on the last day of every 3rd month").
                            __( '%1$s on the last day of every %2$s month', 'woocommerce-subscriptions' ),
                            $price,
                            wcs_append_numeral_suffix( $billing_interval )
                         );
                      } else {
                         $subscription_string .= sprintf(
                         // translators: 1$: <price> on the, 2$: <date> day of every, 3$: <interval> month (e.g. "$10 on the 23rd day of every 2nd month").
                            __( '%1$s on the %2$s day of every %3$s month', 'woocommerce-subscriptions' ),
                            $price,
                            wcs_append_numeral_suffix( $payment_day ),
                            wcs_append_numeral_suffix( $billing_interval )
                         );
                      }
                   }
                   break;
                case 'year':
                   if ( 1 === $billing_interval ) {
                      $subscription_string .= sprintf(
                      // translators: 1$: <price> on, 2$: <date>, 3$: <month> each year (e.g. "$15 on March 15th each year").
                         __( '%1$s on %2$s %3$s each year', 'woocommerce-subscriptions' ),
                         $price,
                         $wp_locale->month[ $payment_day['month'] ],
                         wcs_append_numeral_suffix( $payment_day['day'] )
                      );
                   } else {
                      $subscription_string .= sprintf(
                      // translators: 1$: recurring amount, 2$: month (e.g. "March"), 3$: day of the month (e.g. "23rd").
                         __( '%1$s on %2$s %3$s every %4$s year', 'woocommerce-subscriptions' ),
                         $price,
                         $wp_locale->month[ $payment_day['month'] ],
                         wcs_append_numeral_suffix( $payment_day['day'] ),
                         wcs_append_numeral_suffix( $billing_interval )
                      );
                   }
                   break;
             }
          } else {
             $subscription_string = sprintf(
             // translators: 1$: recurring amount, 2$: subscription period (e.g. "month" or "3 months") (e.g. "$15 / month" or "$15 every 2nd month").
                _n( '%1$s / %2$s', '%1$s every %2$s', $billing_interval, 'woocommerce-subscriptions' ),
                $price,
                wcs_get_subscription_period_strings( $billing_interval, $billing_period )
             );
          }
       } elseif ( $include['subscription_price'] ) {
          $subscription_string = $price;
       } elseif ( $include['subscription_period'] ) {
          $subscription_string = '<span class="subscription-details">' . sprintf(
             // translators: billing period (e.g. "every week").
                __( 'every %s', 'woocommerce-subscriptions' ),
                wcs_get_subscription_period_strings( $billing_interval, $billing_period )
             );
       } else {
          $subscription_string = '<span class="subscription-details">';
       }

       // Add the length to the end.
       if ( $include_length ) {
          // translators: 1$: subscription string (e.g. "$10 up front then $5 on March 23rd every 3rd year"), 2$: length (e.g. "4 years").
          $subscription_string = sprintf( __( '%1$s for %2$s', 'woocommerce-subscriptions' ), $subscription_string, $ranges[ $subscription_length ] );
       }

       if ( $include['trial_length'] && 0 !== $trial_length ) {
          $trial_string = wcs_get_subscription_trial_period_strings( $trial_length, $trial_period );
          // translators: 1$: subscription string (e.g. "$15 on March 15th every 3 years for 6 years"), 2$: trial length (e.g.: "with 4 months free trial").
          $subscription_string = sprintf( __( '%1$s with %2$s free trial', 'woocommerce-subscriptions' ), $subscription_string, $trial_string );
       }

       if ( $include['sign_up_fee'] && \WC_Subscriptions_Product::get_sign_up_fee( $product ) > 0 ) {
          // translators: 1$: subscription string (e.g. "$15 on March 15th every 3 years for 6 years with 2 months free trial"), 2$: signup fee price (e.g. "and a $30 sign-up fee").
          $subscription_string = sprintf( __( '%1$s and a %2$s sign-up fee', 'woocommerce-subscriptions' ), $subscription_string, $sign_up_fee );
       }

       $subscription_string .= '</span>';
       return $subscription_string;
    }
    
    public function fix_subscription_product_price($active_price, $product) {

       $subscription_price = \WC_Subscriptions_Product::get_meta_data( $product, 'subscription_price', 0 );
       $sale_price         = \WC_Subscriptions_Product::get_sale_price( $product );

       if ($subscription_price) {
          global $WOOCS;
          if ($WOOCS->is_multiple_allowed) {
             $subscription_price = $WOOCS->woocs_exchange_value(floatval($subscription_price));
          }
       }
       $active_price = ( $subscription_price ) ? $subscription_price : self::get_regular_price( $product );

       // Ensure that $sale_price is non-empty because other plugins can use woocommerce_product_is_on_sale filter to
       // forcefully set a product's is_on_sale flag (like Dynamic Pricing )
       if ( $product->is_on_sale() && '' !== $sale_price && $subscription_price > $sale_price ) {
          $active_price = $sale_price;
       }
       return $active_price;
    }
    public function fix_renewal_product_title( $line_item_name, $_product) {
       global $WOOCS;
       if ($WOOCS->is_multiple_allowed) {
          // TODO: get subscription object.
          $curr = get_post_meta($subscription->get_id(), '_order_currency', true);
          $currencies = $WOOCS->get_currencies();
          $rate = $currencies[$curr]['rate'];
          $price = $price / ($rate);
       }
       return $line_item_name;
    }
    public function adjust_cart_item_price_from_session($cart_item_session_data, $cart_item, $key) {

       /** @var \WCS_Cart_Renewal $cart_renewal */
       $cart_renewal = \WC_Subscriptions_Core_Plugin::instance()->get_cart_handler(\WCS_Cart_Renewal::class);
       if ( $cart_renewal->should_honor_subscription_prices( $cart_item ) ) {
          $cart_item_session_data[ $this->cart_item_key ] = $cart_item[ $cart_renewal->cart_item_key ];

          $_product = $cart_item_session_data['data'];

          // Need to get the original subscription or order price, not the current price
          $subscription = wc_get_order( $cart_item[ $cart_renewal->cart_item_key ]['renewal_order_id'] );

          if ( $subscription ) {
             $subscription_items = $subscription->get_items();
             $item_to_renew      = [];

             /**
              * Find the subscription or order line item that represents this cart item.
              *
              * If cart item data correctly records a valid line item ID, use that to find the line item.
              * Otherwise, use the cart item key stored in line item meta.
              */
             if ( isset( $subscription_items[ $cart_item_session_data[ $cart_renewal->cart_item_key ]['line_item_id'] ] ) ) {
                $item_to_renew = $subscription_items[ $cart_item_session_data[ $cart_renewal->cart_item_key ]['line_item_id'] ];
             } else {
                foreach ( $subscription_items as $item ) {
                   if ( $item->get_meta( '_cart_item_key_' . $cart_renewal->cart_item_key, true ) === $key ) {
                      $item_to_renew = $item;
                      break;
                   }
                }
             }

             // If we can't find the item to renew, return the cart item session data as is.
             if ( empty( $item_to_renew ) ) {
                return $cart_item_session_data;
             }

             $price = $item_to_renew['line_subtotal'];

             if ( $_product->is_taxable() && $subscription->get_prices_include_tax() ) {

                // If this item's subtracted tax data hasn't been repaired, do that now.
                if ( isset( $item_to_renew['_subtracted_base_location_tax'] ) ) {
                   \WC_Subscriptions_Upgrader::repair_subtracted_base_taxes( $item_to_renew->get_id() );

                   // The item has been updated so get a refreshed version of the item.
                   $item_to_renew = \WC_Order_Factory::get_order_item( $item_to_renew->get_id() );
                }

                if ( isset( $item_to_renew['_subtracted_base_location_taxes'] ) ) {
                   $price += array_sum( $item_to_renew['_subtracted_base_location_taxes'] ) * $item_to_renew['qty'];
                } elseif ( isset( $item_to_renew['taxes']['subtotal'] ) ) {
                   $price += array_sum( $item_to_renew['taxes']['subtotal'] ); // Use the taxes array items here as they contain taxes to a more accurate number of decimals.
                }
             }

             global $WOOCS;
             if ($WOOCS->is_multiple_allowed) {
                $curr = $subscription->get_meta('_order_currency');
                $currencies = $WOOCS->get_currencies();
                $rate = $currencies[$curr]['rate'];
                $price = $price / ($rate);
             }

             // In rare cases quantity can be zero. Check first to prevent triggering a fatal error in php8+
             if ( 0 !== (int) $item_to_renew['qty'] ) {
                $_product->set_price( $price / $item_to_renew['qty'] );
             }

             // Don't carry over any sign up fee
             wcs_set_objects_property( $_product, 'subscription_sign_up_fee', 0, 'set_prop_only' );

             // Allow plugins to add additional strings to the product name for renewals
             $line_item_name = is_callable( $item_to_renew, 'get_name' ) ? $item_to_renew->get_name() : $item_to_renew['name'];
             wcs_set_objects_property( $_product, 'name', apply_filters( 'woocommerce_subscriptions_renewal_product_title', $line_item_name, $_product ), 'set_prop_only' );

             // Make sure the same quantity is renewed
             $cart_item_session_data['quantity'] = $item_to_renew['qty'];
          }
       }

       return $cart_item_session_data;
    }
}

add_action('plugins_loaded', function () {
    if ( class_exists( 'WOOCS' ) && class_exists( 'WC_Subscriptions' ) ) {
       $wcs_compatibilty = new WOOCS_Subscription_Fix();
       $wcs_compatibilty->init();
    }
});

This can be added to a file in wp-content/mu-plugins/fox-fix.php to fix the problem on any site. I've tested it myself but I'd appreciate it if support could test it as well as I'm sure you'll be better able to identify any edge cases I may have missed.

Thanks

<?php
/**
 * Plugin Name:  Fix FOX multicurrency with Woocommerece Subscriptions.
 * Description:  Fix CSS
 * Version:      1.0.0
 * Author:       Dave
 * License:      MIT License
 */

/**
 * Class WOOCS_Subscription_Fix
 * Handles WooCommerce Currency Switcher (WOOCS) fixes for WooCommerce Subscriptions
 */
class WOOCS_Subscriptions_Compatibility {
    
    /**
     * Initialize the filters
     */
    public function init() {

       // Subscription price string details
       add_filter('woocommerce_subscription_price_string_details',
          [$this, 'fix_subscription_price_string_details'], 100, 2);

       // Get subscription orders
       add_filter('wcs_get_subscription_orders',
          [$this, 'fix_subscription_orders'], 10, 3);

       // New order items
       add_filter('wcs_new_order_items',
          [$this, 'fix_new_order_items'], 2, 3);

       // Variable subscription price HTML
       add_filter('woocommerce_variable_subscription_price_html',
          [$this, 'fix_variable_subscription_price_html'], 10, 2);

       // Subscription product price string
       add_filter('woocommerce_subscriptions_product_price_string',
          [$this, 'fix_subscription_product_price_string'], 10, 3);

       // Subscription product price
       add_filter('woocommerce_subscriptions_product_price',
          [$this, 'fix_subscription_product_price'], 10, 2);

       // Renewal product title
       add_filter('woocommerce_subscriptions_renewal_product_title',
          [$this, 'fix_renewal_product_title'], 10, 2);

       // Cart item from session
       remove_filter('woocommerce_get_cart_item_from_session',
          [WC_Subscriptions_Core_Plugin::instance()->get_cart_handler(WCS_Cart_Renewal::class), 'add_cart_item_data']);
       add_filter('woocommerce_get_cart_item_from_session',
          [$this, 'adjust_cart_item_price_from_session'], 12, 3);
    }

    public function fix_subscription_price_string_details() {
       global $WOOCS;

       $order_currency = $subscription->get_meta('_order_currency');
       if ($order_currency && $WOOCS->current_currency !== $order_currency) {
          $WOOCS->set_currency($order_currency);
       }
       return $arg;
    }
    public function fix_subscription_orders ( $orders, $return_fields, $order_type) {

       if ( 'all' === $return_fields ) {
          foreach ( $orders as $order ) {
             global $WOOCS;
             $order_currency = $order->get_meta('_order_currency');
             if ($order_currency && $WOOCS->current_currency != $order_currency) {
                $WOOCS->set_currency($order_currency);
             }
          }
       }
       return $orders;
    }
    public function fix_new_order_items($items, $new_order, $subscription ) {
       global $WOOCS;
       $order_currency = $subscription->get_meta('_order_currency');
       if ($order_currency && $WOOCS->current_currency != $order_currency) {
          $WOOCS->set_currency($order_currency);
       }
       return $items;
    }

    public function fix_variable_subscription_price_html( $price, $product ) {
       $prices                 = $product->get_variation_prices( true );
       $min_price_variation_id = $product->get_meta( '_min_price_variation_id' );

       $tax_display_mode = get_option( 'woocommerce_tax_display_shop' );

       $price = \WC_Subscriptions_Product::get_price( $min_price_variation_id );
       if (isset($prices['price'][$min_price_variation_id])) {
          $price = $prices['price'][$min_price_variation_id];
       }
       $price = 'incl' == $tax_display_mode ? wcs_get_price_including_tax( $product, array( 'price' => $price ) ) : wcs_get_price_excluding_tax( $product, array( 'price' => $price ) );
       $price = $product->get_price_prefix( $prices ) . wc_price( $price ) . $product->get_price_suffix();
       $price = apply_filters( 'woocommerce_variable_price_html', $price, $product );
       $price = \WC_Subscriptions_Product::get_price_string( $product, array( 'price' => $price ) );

       return $price;
    }
    public function fix_subscription_product_price_string($subscription_string, $product, $include ) {
       global $wp_locale;

       if ( ! \WC_Subscriptions_Product::is_subscription( $product ) ) {
          return;
       }

       $base_price          = \WC_Subscriptions_Product::get_price( $product );
       $billing_interval    = (int) \WC_Subscriptions_Product::get_interval( $product );
       $billing_period      = \WC_Subscriptions_Product::get_period( $product );
       $subscription_length = (int) \WC_Subscriptions_Product::get_length( $product );
       $trial_length        = (int) \WC_Subscriptions_Product::get_trial_length( $product );
       $trial_period        = \WC_Subscriptions_Product::get_trial_period( $product );
       $sign_up_fee         = 0;
       $include_length      = $include['subscription_length'] && 0 !== $subscription_length;

       if ( empty( $billing_period ) ) {
          $billing_period = 'month';
       }

       if ( $include_length ) {
          $ranges = wcs_get_subscription_ranges( $billing_period );
       }

       if ( $include['sign_up_fee'] ) {
          $sign_up_fee = is_bool( $include['sign_up_fee'] ) ? \WC_Subscriptions_Product::get_sign_up_fee( $product ) : $include['sign_up_fee'];
       }

       if ( $include['tax_calculation'] ) {
          if ( in_array( $include['tax_calculation'], array( 'exclude_tax', 'excl' ), true ) ) {
             // Calculate excluding tax.
             $price = isset( $include['price'] ) ? $include['price'] : wcs_get_price_excluding_tax( $product );
             if ( true === $include['sign_up_fee'] ) {
                $sign_up_fee = wcs_get_price_excluding_tax( $product, array( 'price' => \WC_Subscriptions_Product::get_sign_up_fee( $product ) ) );
             }
          } else {
             // Calculate including tax.
             $price = isset( $include['price'] ) ? $include['price'] : wcs_get_price_including_tax( $product );
             if ( true === $include['sign_up_fee'] ) {
                $sign_up_fee = wcs_get_price_including_tax( $product, array( 'price' => \WC_Subscriptions_Product::get_sign_up_fee( $product ) ) );
             }
          }
       } else {
          $price = isset( $include['price'] ) ? $include['price'] : wc_price( $base_price );
       }

       if ( is_numeric( $sign_up_fee ) ) {
          global $WOOCS;
          if ($WOOCS->is_multiple_allowed) {
             $sign_up_fee = $WOOCS->woocs_exchange_value(floatval($sign_up_fee));
          }
          $sign_up_fee = wc_price( $sign_up_fee );
       }

       $price .= ' <span class="subscription-details">';

       $subscription_string = '';

       if ( $include['subscription_price'] && $include['subscription_period'] ) { // Allow extensions to not show price or billing period e.g. Name Your Price.
          if ( $include_length && $subscription_length === $billing_interval ) {
             $subscription_string = $price; // Only for one billing period so show"$5 for 3 months" instead of"$5 every 3 months for 3 months".
          } elseif ( \WC_Subscriptions_Synchroniser::is_product_synced( $product ) && in_array( $billing_period, array( 'week', 'month', 'year' ), true ) ) {
             $subscription_string = '';

             if ( \WC_Subscriptions_Synchroniser::is_payment_upfront( $product ) && ! \WC_Subscriptions_Synchroniser::is_today( \WC_Subscriptions_Synchroniser::calculate_first_payment_date( $product, 'timestamp' ) ) ) {
                /* translators: %1$s refers to the price. This string is meant to prefix another string below, e.g."$5 now, and $5 on March 15th each year" */
                $subscription_string = sprintf( __( '%1$s now, and ', 'woocommerce-subscriptions' ), $price );
             }

             $payment_day = \WC_Subscriptions_Synchroniser::get_products_payment_day( $product );
             switch ( $billing_period ) {
                case 'week':
                   $payment_day_of_week = \WC_Subscriptions_Synchroniser::get_weekday( $payment_day );
                   if ( 1 === $billing_interval ) {
                      // translators: 1$: recurring amount string, 2$: day of the week (e.g."$10 every Wednesday").
                      $subscription_string .= sprintf( __( '%1$s every %2$s', 'woocommerce-subscriptions' ), $price, $payment_day_of_week );
                   } else {
                      $subscription_string .= sprintf(
                      // translators: 1$: recurring amount string, 2$: period, 3$: day of the week (e.g."$10 every 2nd week on Wednesday").
                         __( '%1$s every %2$s on %3$s', 'woocommerce-subscriptions' ),
                         $price,
                         wcs_get_subscription_period_strings( $billing_interval, $billing_period ),
                         $payment_day_of_week
                      );
                   }
                   break;
                case 'month':
                   if ( 1 === $billing_interval ) {
                      if ( $payment_day > 27 ) {
                         // translators: placeholder is recurring amount.
                         $subscription_string .= sprintf( __( '%s on the last day of each month', 'woocommerce-subscriptions' ), $price );
                      } else {
                         $subscription_string .= sprintf(
                         // translators: 1$: recurring amount, 2$: day of the month (e.g."23rd") (e.g."$5 every 23rd of each month").
                            __( '%1$s on the %2$s of each month', 'woocommerce-subscriptions' ),
                            $price,
                            wcs_append_numeral_suffix( $payment_day )
                         );
                      }
                   } else {
                      if ( $payment_day > 27 ) {
                         $subscription_string .= sprintf(
                         // translators: 1$: recurring amount, 2$: interval (e.g."3rd") (e.g."$10 on the last day of every 3rd month").
                            __( '%1$s on the last day of every %2$s month', 'woocommerce-subscriptions' ),
                            $price,
                            wcs_append_numeral_suffix( $billing_interval )
                         );
                      } else {
                         $subscription_string .= sprintf(
                         // translators: 1$: <price> on the, 2$: <date> day of every, 3$: <interval> month (e.g."$10 on the 23rd day of every 2nd month").
                            __( '%1$s on the %2$s day of every %3$s month', 'woocommerce-subscriptions' ),
                            $price,
                            wcs_append_numeral_suffix( $payment_day ),
                            wcs_append_numeral_suffix( $billing_interval )
                         );
                      }
                   }
                   break;
                case 'year':
                   if ( 1 === $billing_interval ) {
                      $subscription_string .= sprintf(
                      // translators: 1$: <price> on, 2$: <date>, 3$: <month> each year (e.g."$15 on March 15th each year").
                         __( '%1$s on %2$s %3$s each year', 'woocommerce-subscriptions' ),
                         $price,
                         $wp_locale->month[ $payment_day['month'] ],
                         wcs_append_numeral_suffix( $payment_day['day'] )
                      );
                   } else {
                      $subscription_string .= sprintf(
                      // translators: 1$: recurring amount, 2$: month (e.g."March"), 3$: day of the month (e.g."23rd").
                         __( '%1$s on %2$s %3$s every %4$s year', 'woocommerce-subscriptions' ),
                         $price,
                         $wp_locale->month[ $payment_day['month'] ],
                         wcs_append_numeral_suffix( $payment_day['day'] ),
                         wcs_append_numeral_suffix( $billing_interval )
                      );
                   }
                   break;
             }
          } else {
             $subscription_string = sprintf(
             // translators: 1$: recurring amount, 2$: subscription period (e.g."month" or"3 months") (e.g."$15 / month" or"$15 every 2nd month").
                _n( '%1$s / %2$s', '%1$s every %2$s', $billing_interval, 'woocommerce-subscriptions' ),
                $price,
                wcs_get_subscription_period_strings( $billing_interval, $billing_period )
             );
          }
       } elseif ( $include['subscription_price'] ) {
          $subscription_string = $price;
       } elseif ( $include['subscription_period'] ) {
          $subscription_string = '<span class="subscription-details">' . sprintf(
             // translators: billing period (e.g."every week").
                __( 'every %s', 'woocommerce-subscriptions' ),
                wcs_get_subscription_period_strings( $billing_interval, $billing_period )
             );
       } else {
          $subscription_string = '<span class="subscription-details">';
       }

       // Add the length to the end.
       if ( $include_length ) {
          // translators: 1$: subscription string (e.g."$10 up front then $5 on March 23rd every 3rd year"), 2$: length (e.g."4 years").
          $subscription_string = sprintf( __( '%1$s for %2$s', 'woocommerce-subscriptions' ), $subscription_string, $ranges[ $subscription_length ] );
       }

       if ( $include['trial_length'] && 0 !== $trial_length ) {
          $trial_string = wcs_get_subscription_trial_period_strings( $trial_length, $trial_period );
          // translators: 1$: subscription string (e.g."$15 on March 15th every 3 years for 6 years"), 2$: trial length (e.g.:"with 4 months free trial").
          $subscription_string = sprintf( __( '%1$s with %2$s free trial', 'woocommerce-subscriptions' ), $subscription_string, $trial_string );
       }

       if ( $include['sign_up_fee'] && \WC_Subscriptions_Product::get_sign_up_fee( $product ) > 0 ) {
          // translators: 1$: subscription string (e.g."$15 on March 15th every 3 years for 6 years with 2 months free trial"), 2$: signup fee price (e.g."and a $30 sign-up fee").
          $subscription_string = sprintf( __( '%1$s and a %2$s sign-up fee', 'woocommerce-subscriptions' ), $subscription_string, $sign_up_fee );
       }

       $subscription_string .= '</span>';
       return $subscription_string;
    }
    
    public function fix_subscription_product_price($active_price, $product) {

       $subscription_price = \WC_Subscriptions_Product::get_meta_data( $product, 'subscription_price', 0 );
       $sale_price         = \WC_Subscriptions_Product::get_sale_price( $product );

       if ($subscription_price) {
          global $WOOCS;
          if ($WOOCS->is_multiple_allowed) {
             $subscription_price = $WOOCS->woocs_exchange_value(floatval($subscription_price));
          }
       }
       $active_price = ( $subscription_price ) ? $subscription_price : self::get_regular_price( $product );

       // Ensure that $sale_price is non-empty because other plugins can use woocommerce_product_is_on_sale filter to
       // forcefully set a product's is_on_sale flag (like Dynamic Pricing )
       if ( $product->is_on_sale() && '' !== $sale_price && $subscription_price > $sale_price ) {
          $active_price = $sale_price;
       }
       return $active_price;
    }
    public function fix_renewal_product_title( $line_item_name, $_product) {
       global $WOOCS;
       if ($WOOCS->is_multiple_allowed) {
          // TODO: get subscription object.
          $curr = get_post_meta($subscription->get_id(), '_order_currency', true);
          $currencies = $WOOCS->get_currencies();
          $rate = $currencies[$curr]['rate'];
          $price = $price / ($rate);
       }
       return $line_item_name;
    }
    public function adjust_cart_item_price_from_session($cart_item_session_data, $cart_item, $key) {

       /** @var \WCS_Cart_Renewal $cart_renewal */
       $cart_renewal = \WC_Subscriptions_Core_Plugin::instance()->get_cart_handler(\WCS_Cart_Renewal::class);
       if ( $cart_renewal->should_honor_subscription_prices( $cart_item ) ) {
          $cart_item_session_data[ $this->cart_item_key ] = $cart_item[ $cart_renewal->cart_item_key ];

          $_product = $cart_item_session_data['data'];

          // Need to get the original subscription or order price, not the current price
          $subscription = wc_get_order( $cart_item[ $cart_renewal->cart_item_key ]['renewal_order_id'] );

          if ( $subscription ) {
             $subscription_items = $subscription->get_items();
             $item_to_renew      = [];

             /**
              * Find the subscription or order line item that represents this cart item.
              *
              * If cart item data correctly records a valid line item ID, use that to find the line item.
              * Otherwise, use the cart item key stored in line item meta.
              */
             if ( isset( $subscription_items[ $cart_item_session_data[ $cart_renewal->cart_item_key ]['line_item_id'] ] ) ) {
                $item_to_renew = $subscription_items[ $cart_item_session_data[ $cart_renewal->cart_item_key ]['line_item_id'] ];
             } else {
                foreach ( $subscription_items as $item ) {
                   if ( $item->get_meta( '_cart_item_key_' . $cart_renewal->cart_item_key, true ) === $key ) {
                      $item_to_renew = $item;
                      break;
                   }
                }
             }

             // If we can't find the item to renew, return the cart item session data as is.
             if ( empty( $item_to_renew ) ) {
                return $cart_item_session_data;
             }

             $price = $item_to_renew['line_subtotal'];

             if ( $_product->is_taxable() && $subscription->get_prices_include_tax() ) {

                // If this item's subtracted tax data hasn't been repaired, do that now.
                if ( isset( $item_to_renew['_subtracted_base_location_tax'] ) ) {
                   \WC_Subscriptions_Upgrader::repair_subtracted_base_taxes( $item_to_renew->get_id() );

                   // The item has been updated so get a refreshed version of the item.
                   $item_to_renew = \WC_Order_Factory::get_order_item( $item_to_renew->get_id() );
                }

                if ( isset( $item_to_renew['_subtracted_base_location_taxes'] ) ) {
                   $price += array_sum( $item_to_renew['_subtracted_base_location_taxes'] ) * $item_to_renew['qty'];
                } elseif ( isset( $item_to_renew['taxes']['subtotal'] ) ) {
                   $price += array_sum( $item_to_renew['taxes']['subtotal'] ); // Use the taxes array items here as they contain taxes to a more accurate number of decimals.
                }
             }

             global $WOOCS;
             if ($WOOCS->is_multiple_allowed) {
                $curr = $subscription->get_meta('_order_currency');
                $currencies = $WOOCS->get_currencies();
                $rate = $currencies[$curr]['rate'];
                $price = $price / ($rate);
             }

             // In rare cases quantity can be zero. Check first to prevent triggering a fatal error in php8+
             if ( 0 !== (int) $item_to_renew['qty'] ) {
                $_product->set_price( $price / $item_to_renew['qty'] );
             }

             // Don't carry over any sign up fee
             wcs_set_objects_property( $_product, 'subscription_sign_up_fee', 0, 'set_prop_only' );

             // Allow plugins to add additional strings to the product name for renewals
             $line_item_name = is_callable( $item_to_renew, 'get_name' ) ? $item_to_renew->get_name() : $item_to_renew['name'];
             wcs_set_objects_property( $_product, 'name', apply_filters( 'woocommerce_subscriptions_renewal_product_title', $line_item_name, $_product ), 'set_prop_only' );

             // Make sure the same quantity is renewed
             $cart_item_session_data['quantity'] = $item_to_renew['qty'];
          }
       }

       return $cart_item_session_data;
    }
}

add_action('plugins_loaded', function () {
    if ( class_exists( 'WOOCS' ) && class_exists( 'WC_Subscriptions' ) ) {
       $wcs_compatibilty = new WOOCS_Subscription_Fix();
       $wcs_compatibilty->init();
    }
});

This can be added to a file in wp-content/mu-plugins/fox-fix.php to fix the problem on any site. I've tested it myself but I'd appreciate it if support could test it as well as I'm sure you'll be better able to identify any edge cases I may have missed.