Yes, and privately. We actually utilize the warning point system, so usually there has been some disciplinary action and attempts to correct the individual first.
If they ask, then I might, most of the time I do not 😉 and members don't ask unless they already know about it but end of the day I keep it inside with staff members
I think I have only mentioned ban reasons to a small crowd only a few times this past 10 years. A large majority of the time, I would generally just keep it to staff and a few key people I feel needs to know (to make sure the user doesn't cause trouble elsewhere).
As much as possible I always try to handle moderation as discreetly as possible so something as big as a banning would have to take place, as much as the situation allows for it, in private. It would be a last resort and from them it is up to them. I am not a fan of making it a big spectacle.
If it is a serious offense, I'm considering adding that in, but if its multiple small infractions, then we probably won't make note of it.
Or if its a private matter, then we won't either. But if its like, one of our cardinal rules (as a PG community, multiple swearing offenses would count), then we will.
I actually feel that if members should ask why a particular user was banned, in the spirit of open communication, the admin has to let them know the reason. If they don't ask, you are not under obligation to reveal the reason for a ban.