Starting from SXA 10.1.0, redirect map entries might not be redirected for sites with a virtual folder in the site definition. The issue occurs because the Redirect map does not consider the virtual folder in the original URL path by default. This results in a 404 HTTP error.

To mitigate the issue, mention your virtual folder in the redirect map explicitly or via SXA token:

/[virtual folder]/old page >> /new page
or
/$vf/old page >> /new page

instead of
/old page >> /new page