The hreflang “x-default” attribute price signals to Google algorithms that the web page doesn’t focus on any unique language or locale and it is the default site when no other web page is better suited. As mentioned higher than, the hreflang and canonical tags have slight dissimilarities inside their use https://addons.prestashop.com/en/seo-natural-search-engine-optimization/30904-automatic-hreflang-tags-canonical-tags-all-pages-seo.html