AMP Page URL is Redirect (3XX)
This means that the URL in question defines an AMP Page URL that is a Redirect (3XX).
Why is this important?
If an AMP Page URL redirects, search engines may end up on the wrong page, which means it may not get indexed properly or appear in search results.
What does the Hint check?
This Hint will trigger for any internal URL which references an AMP Page, where the AMP page URL returns a 3XX HTTP header response.
Examples that trigger this Hint
Consider the URL: https://example.com/page-a/
The Hint would trigger for this URL if it included a <link> tag that referenced an AMP page:
where this AMP page had a 301 (Permanent Redirect) header response:
Similarly, URLs with other 'redirect' statuses will trigger the Hint (i.e. any other 3XX response).
How do you resolve this issue?
AMP URLs need to be accessible in order to be indexed. In this case, the AMP URL redirects to another URL, which may be the incorrect one. Even if it is the correct one, the redirect adds an additional 'hop' for search engines, which may cause them to ignore the AMP page or not include it in search results.
To rectify, you would need to ensure that the <link> tag is pointing to the correct (i.e. equivalent) AMP page, and ensure that this page is fully accessible to search engines and users alike, returning a 200 HTTP response.