Crash and loss of streak
Sometimes the game crashes, as it happens with practically all the programs, I can understand and accept it. The problem is that after such a crash it is impossible to restore the streak, though in case of loss you can pay the penalty and continue it.
I understand that it is practically impossible to distinguish between real crash and forced by cheating user crash, I can even understand that it could be difficult to record the score right before the crash (to see who was indeed winning to keep fair game play approach). But such real crashes do not happen often, so why not to let user count it as a loss? For example, my streak was slightly above 700, and I would gladly pay the penalty (less than 100 gems) even after such a crash (I did not have any crashes from May, when the version after update became unstable, but it was fixed almost immediately)!