I’ve been noticing this more and more in the modlogs, with it proven via the “creator” option in some instances’ modlogs that the people doing the bans were mods and not admins, and when I first joined Lemmy, one of the things that were held as a universal truth was that this absolutely could not happen.
Admins have full control over the entire instance. Of course they get mod options in communities they aren’t necessarily mods of on their instance.