Blocked communities still appear on home page...?

Originally planned to slowly whittle away at the stream of topics hitting local and all so that the ones I’m not interested in don’t appear. Couple weeks into that, and I’m noticing communities I’ve blocked are still showing up. Figured it was a similarly named community on another instance, so I navigated to it to hit the block button, but there’s a big red “unblock community” button instead, so this one’s definitely already on the list.

Is this working as intended? And if yes, what is blocking aimed to do?