VRChat 2018.2.1 introduced OnOwnershipTransfer trigger. https://docs.vrchat.com/docs/vrchat-201821

> OnOwnershipTransfer - Used to detect when the ownership of an ObjectSync object ha changed

But, this OnOwnershipTransfer trigger fires when the ownership of *any* ObjectSync objects in the scene has changed.

Excepting a case that has only one ObjectSync object in the scene, this is useless. Especially, prefabs can't use this trigger because they can't put assumption of another ObjectSync objects.