Funnily enough in jujutsu kaisen many of the people who got transfigured by patchwork face die of shock because their mind doesn’t accept their new body as their. Also I vaguely remember an experiment where surgeons were trying to transplant a entire head. And one of the many issues was the fact that the brain kept waking up and rejecting the body because of small differences like a vain being in the wrong spot. I really need to dig that study up I remember it being a pretty neat and oddly terrifying read.