90fps problem in Iphone 13 pro max – PUBG MOBILE Review

I have been using 13 pro max since 2 months and i can’t play it on 90fps . When i play it on 90fps it lags and fps drops to 10,20 fps i checked the device and took it to Apple care they said everything is perfect the problem is of the software … Can you help in this by updating or so on.
Review by monsterdepes on PUBG MOBILE.