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.
its called cross-banning. reddit does this when problematic conservative subreddits have potential spammers and voters. but it also unilaterally bans innoncent users, which puts them in a vulnerable poisiton to be sitewide banned.