Fix add_to_cart event not firing on Woo Product where theme uses custom ajax event

functions.php

<?php
/**
 * GA4 event: add_to_cart
 */
add_action('wp_footer', function() {
    if (!is_product()) return;
    ?>
    <script type="text/javascript">
        // track add to cart events for products on product detail pages
        jQuery(document).ready(function($) {
            $(document).ajaxSuccess(function(event, xhr, settings) {
                if ( xhr.status == 200 &&
                     xhr.responseText &&
                     xhr.responseText.indexOf('popup') !== -1 &&
                     settings.data &&
                     settings.data.indexOf( 'woocommerce_ajax_add_to_cart' ) !== -1
                     ) {
                    let event_target_element = document.querySelector('.js-add-to-cart');

                    if ( !event_target_element ) {
                        // for some reason event target is not specificed
                        return true;
                    }

                    const product_form = event_target_element.closest( 'div.c-product-detail__actions' );
                    if ( !product_form ) {
                        return true;
                    }

                    const product_id_el = gtm4wp_use_sku_instead ? product_form.querySelector( '[name=gtm4wp_sku]' ) : product_form.querySelector( '[name=gtm4wp_id]' );
                    const product_data = {
                        'id':         product_id_el && product_id_el.value,
                        'name':       product_form.querySelector( '[name=gtm4wp_name]' ) && product_form.querySelector( '[name=gtm4wp_name]' ).value,
                        'price':      product_form.querySelector( '[name=gtm4wp_price]' ) && product_form.querySelector( '[name=gtm4wp_price]' ).value,
                        'category':   product_form.querySelector( '[name=gtm4wp_category]' ) && product_form.querySelector( '[name=gtm4wp_category]' ).value,
                        'quantity':   product_form.querySelector( '[name=quantity]' ) && product_form.querySelector( '[name=quantity]' ).value,
                        'stocklevel': product_form.querySelector( '[name=gtm4wp_stocklevel]' ) && product_form.querySelector( '[name=gtm4wp_stocklevel]' ).value,
                        'brand':      product_form.querySelector( '[name=gtm4wp_brand]' ) && product_form.querySelector( '[name=gtm4wp_brand]' ).value
                    };

                    // fire ga4 version
                    window[ gtm4wp_datalayer_name ].push({
                        'event': 'add_to_cart',
                        'ecommerce': {
                            'currency': gtm4wp_currency,
                            'value': product_data.price * product_data.quantity,
                            'items': [ gtm4wp_map_eec_to_ga4( product_data ) ]
                        }
                    });
                }
            });
        });
    </script>
    <?php
}, 20, 1);