so, if you join an instance with physics objects, while in VRChat, in client, the new world starts fine. if you start and launch a new instance from the website, the physics objects explode everywhere

This is easy to replicate. launch the world using this link, then, just go to worlds and make a new instance to see the difference

https://vrchat.com/home/launch?worldId=wrld_bf6b2972-e7bd-48a9-98f0-fb0055281fbb&instanceId=1481~friends(usr_087a641b-da47-4999-b9b5-cd70ee9b904d)~nonce(90c97e3f-6e9d-4ff7-96b1-140f16127fc6)