Ive noticed when both players are in the screan changing the same building settings and or the cross over district screen, it desyncs or the very least desyncs ALOT more, also when you are placing or looking to place a building that does a highlighted zone, for example the logging flagger, it will desync if you move it around too much
also , deconstructing pauses the game and has a chance to desync if not done fast enough
From discord: