It is pretty bad. Games require that you adjust your brightness/HDR calibration within the game. For games that support HDR that’s usually all it takes. It’s either under video or general/game.
For games that don’t support HDR, you’re generally better off turning off Windows HDR completely. Auto HDR is hit or miss. For some games it works, for most it does not. WIN + ALT + B swaps HDR mode, so if I know a game doesn’t support HDR I just swap back to SDR before playing.