I see what you are saying, I happen to spec some games with Muted2021 and his account variations (Muted2020, Muted...).
He seems to be sending huge messages to all the players, thats cause players to drop and himself in the process.
I unmask him to the players in game and he stopped, seems like he did not want any trouble, but you said he continued doing it, so, idk...
This is not the same as the DDOS guy, but still worth looking at.
I forgot to record him and my suggestion is to limit message size, if that is possible.