Did you get any other error before that?

Can you give us the error, please?

That information is stored in the database of the instance you’re on. Note that this only affects the UI. It does nothing more than make blocked users invisible for you. They can fully interact with your posts, comments, view your profile, etc.

Hm, true. I guess site bans are simply not federated. You’ll have to look it up manually, for example when you can’t access any communities of that instance. You might want to ask about this and about the possibility of having site bans from remote instances federate in this community.

Check the modlog and filter by your user.

The not expandable ones are categorized as a Link and the expandable one as a Image.