I used to see this on Reddit, I’m disappointed this behaviour is also on Lemmy.
Users collecting mod status on multiple communities, and then using that power to mass-ban a single user from a bunch of communities.
Modlog show how incredibly trigger happy some mods can be. Minor transgressions, deserving to have their comment removed at least, but then banned from unrelated communities as a consequence. This will only get worse as users become supermods.
Edit: It seems this is how an instance ban is reported, by banning from any communities the user has participated in. Then perhaps it isn’t all as bad as it seems.
Some instances pre-emptively ban users if they happen to have a history of malicious behaviour. Can’t say I can blame the mods and admins for not wanting to put up with the user’s behaviour and the barrage of reports that could follow. Sometimes it’s less of a workload to just ban them than wait for their inevitable trolling.