Penalties can never be reversed even if there is a legitimate problem and screenshots are not conclusive evidence anyways. Continuing to play a high-stakes game mode like Competitive while you see an issue is present is just as bad as deliberately leaving a game. Learn more about this policy here:
If you are still disconnecting today and you need help we can at least help you figure out where and why you might be disconnecting if you run a WinMTR test.