I have the same issue. Sometimes I can't turn right, sometimes i can't accelerate. I've tried remapping to other keys but the problem stays the same and it only occurs ingame in Grid on Stadia. Not in the menu's and I have not (yet) seen it in other games that I spend a lot more time on (i can't spend a lot of time on grid because i get annoyed and stop the game when the controlls stop working. Sometimes it happens in my first race, sometimes after a few.).