This is my first iPhone 13 Pro Max. I did not compare it with any other unit irl, but I have found a plenty of cases online of people reporting the similar problem.My girlfriend have 12 pro max and she doesn't have this problem, when temerature is low the screen is perfect.
Maybe this problem is only on 13 pro/13 pro max. Is your first 13 pro max or you changed your phone? Do you compared with other 13 pro max/13 pro?