There is possibility for foxy doing it mainly because if you check foxy is clearly out of order in fnaf 1 which takes place after the bite of 87 in fnaf 2, foxy has a dislocated jaw as yo-yo can see by looking closely, meaning he may have bitten something to big for his mouth, like a head of an adult guard. There is also speculation from Freddy as he has hand marks from fnaf 1 so he seems to maybe have been doing the bite and Jeremy was trying to push away Freddy, resembled by the handprints on Freddy’s face. The main suspects are mostly Freddy and foxy