The hreflang “x-default” attribute worth alerts to Google algorithms which the web site doesn’t concentrate on any unique language or locale and it is the default page when no other page is healthier suited. Your x-default should not point on your English page. Rather it need to point to a https://addons.prestashop.com/it/seo-indicizzazione-naturale/30904-tag-hreflang-automatici-e-tag-canonici-seo.html