Changed their body so much to the point it's unrecognizable from their past self
I might change one of my character's backstories to be that he made a wish to a god to change his body. His new body was extremely distinct and clearly different from his old one. His DNA is also different, changed by that god. He was 27 years old when he made that wish and this is the first incident in human history where this radical body change wish/process happened.
What would happen to him, legal identity wise? Would he be left stateless/without any identity? Does it depend on how gradual or sudden the body change was (abrupt snap of a fingers vs growing into it slowly across months or years)? Other factors?
The setting is modern day Switzerland.