E_ERROR – Uncaught TypeError: Unsupported operand types

WordPress has send a Critical error alert email today. The website in frontend seems works fine.

WordPress version 6.6.2
ActiveCampaign for WooCommerce (v 2.7.9)
Versione PHP 8.1.29

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ERROR DETAIL
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Un errore di E_ERROR è stato causato nella linea 413 del file /var/www/clients/client1/web12/web/wp-content/plugins/activecampaign-for-woocommerce/includes/orders/class-activecampaign-for-woocommerce-order-action-events.php. Messaggio di errore: Uncaught TypeError: Unsupported operand types: int – string in /var/www/clients/client1/web12/web/wp-content/plugins/activecampaign-for-woocommerce/includes/orders/class-activecampaign-for-woocommerce-order-action-events.php:413
Stack trace:
#0 /var/www/clients/client1/web12/web/wp-content/plugins/activecampaign-for-woocommerce/includes/orders/class-activecampaign-for-woocommerce-order-action-events.php(116): Activecampaign_For_Woocommerce_Order_Action_Events->check_update_validity(Object(Automattic\WooCommerce\Admin\Overrides\Order))
#1 /var/www/clients/client1/web12/web/wp-includes/class-wp-hook.php(326): Activecampaign_For_Woocommerce_Order_Action_Events->execute_order_updated(18377)
#2 /var/www/clients/client1/web12/web/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)
#3 /var/www/clients/client1/web12/web/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#4 /var/www/clients/client1/web12/web/wp-content/plugins/woocommerce/includes/admin/class-wc-admin-meta-boxes.php(263): do_action(‘woocommerce_pro…’, 18377, Object(WP_Post))
#5 /var/www/clients/client1/web12/web/wp-includes/class-wp-hook.php(326): WC_Admin_Meta_Boxes->save_meta_boxes(18377, Object(WP_Post))
#6 /var/www/clients/client1/web12/web/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)
#7 /var/www/clients/client1/web12/web/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#8 /var/www/clients/client1/web12/web/wp-includes/post.php(4891): do_action(‘save_post’, 18377, Object(WP_Post), true)
#9 /var/www/clients/client1/web12/web/wp-includes/post.php(4993): wp_insert_post(Array, false, true)
#10 /var/www/clients/client1/web12/web/wp-admin/includes/post.php(453): wp_update_post(Array)
#11 /var/www/clients/client1/web12/web/wp-admin/post.php(227): edit_post()
#12 {main}
?thrown