While I don’t use Netlify, and maybe a wild guess but another user some time back who also used Netlify seemed to have a similar problem they said below between the <snip> markers:
I’m trying to get Google to index my site’s pages. To assist it, I submitted my sitemap.xml file. Google is saying that the file can be read, but the URLs are invalid.
I have one theory as to what could be causing this, and that is the use of relative URLs. I’m only using them because I want my links to use my domain and not my Netlify subdomain. If I could figure out how to add the _redirects file to the root, that may fix my problem. I’m very new to this whole method of web design and management so I honestly have no idea :-|.
[EDIT UPDATE] Adding the _redirects file to the folder titled “root-files” did the trick.
So perhaps check into that.
The Publii help page for Netlify setup is at: https://getpublii.com/docs/build-a-static-website-with-netlify.html
Maybe others who do use Netlify can help further if you can’t resolve your problem.