Bannings shouldn’t happen by not allowing a person to post no more without telling before. If a moderator thinks of banning somebody the moderator should pm the person in question.
Like that a possible ban won’t be recognized by the public and both parties cap and member can discuss the possibilty of a ban without making noise.
If no agreement arises the member can be banned with or without notice by other forum members.
I’d suggest a “my last words” thread in the forum.