What likely happened is that you had a brief disconnect and the server may not have received your move.
The server is the keeper of the accurate time. With the lag compensation algorithms the times on the clients may not be accurate. That is why you may occasionally see clocks adjusted in games, even without increments.
I know that situation, quite a few times but still guessing it's no hack at all, rather a connection problem. Doesn't need to be a short disconnet on your side, especially reading so many complaints of people with lost connection but very stable internet connection.
As I remember the clock was counting on the opponent but suddenly it was my move and all the counted seconds from the opponent were taken from my clock. So it must looke like a cheat or a bug. I know such common synchronisation problems from the point of view of a software workflow, so I think its a connection problem.
I have a similar game to this a while ago. A few seconds before my opponent's time expires, it adds extra seconds, and then adds a bit more after a few ticks until it goes back up to a minute, and then a minute 2o seconds... I was totally confused, I thought maybe that's how the game I'm playing really is like you can win bonus seconds for every successful escape. I'm just a casual player who doesn't know professional chess rules and theory, but it never happened to me before. This was the game. Check out the ending. I let my clock die to see if I'd get free time like my opponent. Nope! Check it out --
https://www.chess.com/game/live/15427937507
I have a similar game to this a while ago. A few seconds before my opponent's time expires, it adds extra seconds, and then adds a bit more after a few ticks until it goes back up to a minute, and then a minute 2o seconds... I was totally confused, I thought maybe that's how the game I'm playing really is like you can win bonus seconds for every successful escape. I'm just a casual player who doesn't know professional chess rules and theory, but it never happened to me before. This was the game. Check out the ending. I let my clock die to see if I'd get free time like my opponent. Nope! Check it out --
That was a 15|10 game, which means 10 seconds get added to the clock after every move. A player moving quickly enough will see the timer increase. 7 premoves or quick moves and there's over a minute added.
In this instance, it was my opponents move and his clock was ticking down (opponent auto resigned in 3...2....1...0
Yet somehow his move instantly takes place and it was
MY time that expires.
This is impossible because he didn't move and the control didn't shift back to me. (Not to mention I had the game in the bag)
Is this a hack? Has anyone experienced this before?