I've seen a post going around but I can't find it, so I'll recap: uBlock Origin and it's ilk have a rule that breaks loading some of the mastodon components for some instances (idk if it affects mainline masto?)

Ours is one of those instances - it seems to manifest in that you can't open a thread, you'll get an error when you click on a toot to 'zoom in' as it were.

If that's the case, just add an exception or disable uBlock on mastodon.mania.systems and the problem should go away.