It appears the Microsoft Store version of that game has a different config configuration.
There's no SaveData or Preferences folder. And the only thing I get in LocalLow\FuturLab\PowerWash Simulator\ are two files labelled Player.log and Player-prev.log
Though there is a sensitivity line in those files it doesn't change my sensitivity in-game (even setting it as read only) but once I load and close the game the files get updated anyway.