What triggers this issue?
This issue reports pages with at least one link in their hreflang annotations pointing to a non-canonical URL.
Why is it important?
A page linking to a non-canonical URL from its hreflang annotations sends contradictory signals to search engines. On one hand, hreflang annotations instruct search engines about the translated (localized) version of a page to be shown in search results based on users' language and location. On the other hand, the rel=canonical attribute on the alternate page version asks search engines, such as Google, to index another URL instead.
Consequently, search engines may "overlook" alternate versions of your page and will not be able to point users to the most appropriate version of your page by language or region.
How to fix it?
There are two ways to resolve this issue:
You can replace the non-canonical URL in hreflang annotations with its canonical URL.
If the URL specified in hreflang annotations was canonicalized by mistake, turn it into a canonical one. The best way to do that is to add a self-referencing canonical tag to the page.