I've seen plenty of sync errors in my time, but a pattern lately is, after the game is already won and I click "continue playing," perhaps most of the players on one or both sides have left. I will continue playing/destroying the units of the opposing team, and after a few minutes, it says "sync error detected." The timing of it seems to be fairly consistent, which seems to rule out players who are upset that I'm continuing to kill them, although situationally, it makes a lot of sense. There does seem to be a lot of sync hacking going on lately, so I wouldn't rule it out.
It looks like you're new here. If you want to get involved, click one of these buttons!