Is it possible that the limitation for starting games only checks that no new games are made after exactly 20? Like maybe creating game invitations works by not allowing invitations when "games = 20", instead of "games >= 20", which would apply to those who were above pawn level but then go back to pawn.

I don't think it's possible to get above 20 without having already been above 20 before, I'm testing it now and it's not working.