If a user is banned on their home instance, that ban is federated out to all instances. If a user is banned on a remote instance, they're just banned locally on that instance, and their account remains active for all other instances.
They're likely some remote users who have interacted enough with your instance to be federated over, and then banned on their home instance.
Bans coming from mods in communities. They federate moderation out.
If these accounts are just banned from certain communities, then why does it say "banned" in their profiles when viewed from my instance?
Yeah, same concept. Mod or admin actions propagate if they relate to moderation at either level.
This makes the most sense
Same. I've banned a few users, but I have hundreds of users listed as banned. Going by their usernames I probably would have banned many of them myself, but I'm certain that I've never interacted with the vast majority of these accounts. Likewise, I don't know what's going on with that.
