Well the only evidence i guess is how golden freddy twitches in ucn kinda like how springtrap did in the fnaf 3 trailer (which was basically him getting springlocked), but itd also make sense because shes more aggressive than the others, which would mean she probably died a more gruesome death. Also in the give gift give life minigame in fnaf 3, puppet doesnt give the 5th child (cassidy) a gift because her soul is already bound to golden freddy, like how afton is trapped in springtrap with no escape. idk alot of people disagree with it though which is fair, but this is js my guess
