Iphone 13 pro max screeen gets dim while playing cod mobile

I have been experiencing this for some time when I play call of duty mobile on my iPhone 13 pro max the screen will start to dim with the iPhone gets little hot. Granted I believe it was regarding the 5G but it also happend when connected to a wifi. It’s just hard to see the game when the screen dims down so far and I have seen mine go down below 50% because of the heat issue. Once I stop playing after about 2mins the screen brightness randomly brightens.

How to solve this?