Something is really off with the timer at specific days.

This thing is really annoying and preventing me to play at specific days. It's not the first time it happens and I'm noticing it: my connection is great, I have no problems on my side, yet today I lost 2 games getting into time trouble extremely quick without playing really slow. I look at the timings of the games and I see moves that I know I played really quick because I planned them the move before and yet it says "18 seconds" "13 seconds" etc.
Here is an example:
 https://www.chess.com/game/live/97840191169
12. Bb2 - no way it took me 19.9 seconds, I planned on it after I kicked the bishop the move before.
14. Re1 - no way it took me 10 seconds to play it, I already planned to continue with it after exd6.
19. c5 - I planned to do it as he was thinking, again, no way it took me 12.2 seconds.

Something is really wrong here and there are days I just can't play if I don't want to lose all the games. I stopped now after 2 games, but it's really frustrating that I have to stop playing.

Lag can be caused by a lot of different reasons, some our of both the client and site control.

For things you can do to minimize issues, check out the following.

https://support.chess.com/article/4720-online-chess-performance-optimizations

https://support.chess.com/article/213-how-do-i-fix-my-disconnect-lag-issues

I agree that there are timer issues. I had 14 seconds to move a pawn forward. Went to make the play and it killed all 14 seconds and I lost the match. Sometimes it's extremely sporadic, probably is just network latency playing a role sometimes, but it's not fun to suddenly lose like that.

There are a lot of variables in connection quality and that can fluctuate during games.

https://support.chess.com/en/articles/9010617-why-can-t-i-connect-to-chess-com-when-other-sites-are-working-fine