My iphone 15 pro max is getting hot while using camera

That is most likely the problem. The phone shuts down if its temperature exceeds 35ºC (95ºF). Try to keep it out of the sun, and close the camera app except when actually shooting.

Are you using the phone in direct sunlight? If not, that sounds like a hardware problem.

The camera uses a lot of energy and the phone will get warm if the camera is left on for long periods of time, but it should not get hot enough to cause the phone to shut down.