I tried that this morning for fun, and it was way too warm and yellowish for my liking, went back to original.

Nothing out of ordinary. Mostly when it’s charging.

Long time Note/Ultra user, switched to 15 pro max few weeks ago. You have nothing to worry about, it’s a great phone, no issues here whatsoever (except getting used to it). No burn-in, no display issues of any kind, battery life is insane, just relax my man. This thing just works.