Error message on order validation page after enabling the plugin

Hello,

After enabling this plugin, I get this error message on the order validation page:

Notice: Undefined variable: product in /var/www/plv/wp-content/plugins/change-quantity-on-checkout-for-woocommerce/change-quantity-on-checkout-woocommerce.php on line 55

Fatal error: Uncaught Error: Call to a member function get_max_purchase_quantity() on null in /var/www/plv/wp-content/plugins/product-quantity-for-woocommerce-pro/includes/class-alg-wc-pq-core.php:2193 Stack trace: #0 /var/www/plv/wp-content/plugins/product-quantity-for-woocommerce-pro/includes/class-alg-wc-pq-core.php(2215): Alg_WC_PQ_Core->set_quantity_input_min_or_max(69, NULL, 'max') #1 /var/www/plv/wp-includes/class-wp-hook.php(292): Alg_WC_PQ_Core->set_quantity_input_max(69, NULL) #2 /var/www/plv/wp-includes/plugin.php(212): WP_Hook->apply_filters(69, Array) #3 /var/www/plv/wp-content/plugins/change-quantity-on-checkout-for-woocommerce/change-quantity-on-checkout-woocommerce.php(55): apply_filters('woocommerce_qua...', 69, NULL) #4 /var/www/plv/wp-includes/class-wp-hook.php(292): Change_Quantity_On_Checkout->cqoc_add_items('Porte brochures', Array, '88a199611ac2b85...') #5 /var/www/plv/wp-includes/plugin.php(212): WP_Hook->apply_filters('Porte brochures', Array) #6 /var/www/plv/wp-content/plugins/woocommerce/templat in /var/www/plv/wp-content/plugins/product-quantity-for-woocommerce-pro/includes/class-alg-wc-pq-core.php on line 2193

This error prevents the “order” button to display. Any idea what’s causing this?

My plugins:

All in One Product Quantity for WooCommerce Pro v3.8.4
WooCommerce v5.5.2

Thanks for your help.