If they cheat in a USCF event, the USCF should take action. I think they usually ban the player from future vents. This ban might be temporary.
Cheater in USCF tournament / rating refund?
US Chess will not do anything if they are not informed. An opponent or the organizer would need to file an Ethics complaint ($50 filing fee is refunded if the complaint is found to be worthwhile - even if the complaint is subsequently denied).

People sure like to use the word "cheater" a lot on this platform when they lose.
Every time I have received rating points, the explanation was "fair play rules," not cheating. In each case I had a recent game in which I lost on time in a position that would have been a clear win. That's not cheating by the opponent; it's a small gesture from chess.com for people who might otherwise get discouraged and stop participating.
Hi, I got a message from chess.com automated system saying that I was refunded rapid rating for a loss I had in a USCF online rated tournament.
I was wondering if this means that the event report on the USCF website would also need to be rerated; I lost in a very stupid way in under 20 moves, but my opponent’s cheating in other games might have affected others more and I’m curious what the process is in cases like these where the cheating takes place online but in a USCF rated tournament.
The cheater in question has only started playing USCF tournaments last month, so it’s probably safe to assume that he cheated in most of them.
(Edit: Whoops, prolly should have put this in the members-only club)