Is Google actually fetching those pages or are the URLs just showing up in the Google Search Console as “indexed but blocked by robots.txt”?
I don’t see noindex headers on RSS feeds, but if a URL is blocked by robots.txt and has a robots header, the crawler might not ever see the robots header.
[I removed the curl -I output, because it wasn’t using GET, so the robots header was missing.]
Edit: I just checked the RSS feeds with a GET request, because I thought the x-robots-noindex header was on the RSS feeds, and it is there, but only with a GET request.
Now I’m remembering what I did on my main forum. Google Search Console was warning about the RSS URLs being indexed but blocked, so I unblocked the feeds with robots.txt because that prevents Googlebot from fetching the URLs and seeing the noindex header. I’m pretty sure that’s going to resolve the warnings, but I don’t know if it’s going to stop Googlebot from crawling those URLs.
# Disallow: /t/*/*.rss
# Disallow: /c/*.rss
I’d worry a little about telling crawlers that there are RSS feeds (with link, see below) but then sending 404s when the bots try to fetch those URLs. It might lead a machine to think that there is some technical problem with the site, lowering its quality score (however the search engines determine quality or whether a site might be broken for users).
$ curl -s https://meta.discourse.org/latest | grep -i rss
<link rel="alternate" type="application/rss+xml" title="Latest posts" href="https://meta.discourse.org/posts.rss" />
<link rel="alternate" type="application/rss+xml" title="Latest topics" href="https://meta.discourse.org/latest.rss" />
...