This is sadly one of the disadvantages of a touchscreen watch. My Fitbit had the same problem, just because it turns off automatically doesn't mean it doesn't instantly do "odd stuff" when it detects touches.
This is why the Fenix series etc are so great, it's all button driven. Not as "user friendly" you could argue, but none of the random problems in the shower when your watchface changes etc etc.
Everything is a tradeoff