@josh I have seen that happen with the 15Pro on a hot day when attached to a charger on my dashboard in the car and occasionally on really hot days otherwise. I was just surprised as the iPhone didn’t feel hot to the touch and certainly I’ve been out in hotter weather snapping shots.
You could be correct about all the backend stuff going on as a contributing factor, given that I did some filter work requireing I’m sure quite a bit of processing while shooting. But who knows?