Have you ever read Chess.com's explanation of where lag comes from and how Chess.com only controls a very small part of the transmission between you and its servers?
I think it is pretty clear.
If you need help, please contact our Help and Support team.
I lost 16 rating points and lost a tournament just because of a dumb lag. I was just playing a normal tournament until it started lagging and I ended up disconnecting 2 games.
I did a premove and it took away 3 seconds from my timer, timer is going on inspite of it being my opponents turn and my opponent’s timer going from 1 second to 4 seconds in a game with no increment, being paired with others when I have no Internet, the screen being frozen and when I refreshed the chess.com it is showing that I lost a game even though I did not even play a game. Please try fixing this.