This is my face about what Feedly has decided to Cleverly™ do: they'll sometimes fetch my syndication feeds with old Chrome and Firefox user agents, then treat any temporary HTTP redirections they get (to valid syndication feeds) as permanent redirects and directly point their main feed fetchers at the temporary redirect URL. And that is why, if you use Feedly to follow my techblog, you aren't right now.
I have no words for how broken this is, in multiple ways.
https://utcc.utoronto.ca/~cks/space/blog/web/FeedReaderErrorsProblem?showcomments#cks-20260215115901