Other than the timer countdown lagging for people and sometimes being a few seconds ahead of what is read (could be individual connection speeds), there is also another problem when server lags happen, which is when currently running games still have their timers countdown.
This happens for both players so I’m pretty sure it’s a server problem. Could it be adjusted to pause all running games? Synchronize the connectivity of the server to the timers? No player will get affected as neither can play the game anyway. This almost definitely affects all short to blitz games being lost on time for this.