Valid feeds with a # character in the URL are not recognised as RSS feeds

I tried to add this feed:

and get the error message: ‘This address does not point to an RSS feed or a website with an RSS feed.’ (on macOS Safari, in the iOS app it isn’t adding it but no error message is shown).

I have added a similar feed (of another nitter search) recently so this used to work. And the feed validates at Feed Validator Results:

Update: thinking more about this, there are two differences with the feed that worked: a) there were two words being searched for, hence I had quoted the search string and b) it wasn’t a hashtag.

Experimenting with this, I found the issue is with the hashtag. This feeds adds fine:

So there seems to be two issues:

  • Newsblur not being able to add (some) feeds with a %23 in the URL
  • The iOS app not showing an error message when it can’t add a feed