FOX - WooCommerce Currency Switcher Professional

Plugin URL: https://woocommerce.com/products/gift-cards/

In file woocommerce-gift-cards\includes\class-wc-gc-gift-cards.php add next code:

//woocs
if (class_exists('WOOCS')) {
    $meta_data = $giftcard_data->get_meta_data();
    global $WOOCS;
    if (isset($meta_data['_currency']) AND $meta_data['_currency'] != $WOOCS->current_currency) {
        $currencies = $WOOCS->get_currencies();
        if (isset($currencies[$meta_data['_currency']])) {
            $gift_rate = $currencies[$meta_data['_currency']]['rate'];
            $fee_to_apply = $WOOCS->woocs_exchange_value(floatval($fee_to_apply) / $gift_rate);
        }
    }
}