My bluesky feed is somehow even more abhorrent than my twitter one, except that instead of right wing hate it's Facebook memes about "reading banned books"

Bluesky's 'Discover' feed (the default algo feed that you get when you create your account) is based on _likes_, not follows, so if you never like anything you'll get random nonsense.

You can try using other algo feeds from here: https://bsky.app/feeds and remove the discover feed, or of course you could just use the chronological one.