Gift products do not appear in Chrome and on mobile

The plugin has always worked, I set up a promotion in which with a discount code by purchasing a product you receive another as a gift. For a few months, inserting the promotional code woocommerce says “promotional code successfully entered” ì, but you do not see the product as a gift in the cart. This happens with Chrome and on all mobile devices, while on Firefox everything works fine. I updated the WordPress core, the plugins, tried to put previous versions, everything, but it still doesn’t work.

The page I need help with: [log in to see the link]