Nobody should set for a lesser or an inferior quality device when perfect iPhones 12 Pro Max are out there. I had witnessed two iPhones 12 Pro Max (Graphite color), with a perfect screen and not black flickering issue. Also, a friend of mine purchased two iPhones 12 Pro Max on launch day, one blue and one gold, the blue one is yellow-tinted, and the gold is perfect.
Reading all the forums possible, I have learned that there is no correlation between serial numbers and excellent or bad iPhones. Also, it is my opinion that this issue is not related to software. As I said before, there are good ones out there running the same iOS version. The same issue happened to iPhones 11 Pro Max, but it wasn't widespread as the 12 series. Those yellow-tinted iPhones 11 are still yellow-tinted. Apple never produced a fix for it.
I had two iPhones 12 Pro Max, both with the yellow tint, one worst than the other, and one of them all grey colors looked greenish with raised blacks flickering.
If you are on the return period, return it. Tell Apple that you are not going to pay for a defective device.