There is a bug I've seen a few dozen times where a user will be banned in a channel without ever having talked in it or, more importantly, without a record of a ban occurring from any moderators. These bans are always on 7/25/2019, at 4:39 PM, and are often done by someone who wasn't a moderator of the channel at the time. Unbanning these users works as normal, but they need to request an unban or we can't fix anything - meaning we have no idea how widespread this issue is.