SpringConstraint can desync physics, cause streaming replication lag, teleport arbitrary instances to (0,0,0) and break rendering

Repro Place Uncopylocked: Spring Repro - Roblox
To test enter the car’s driver seat and press any of the test buttons.

A video showcasing the repro where by walking into a spring a lot of replication lag is caused, which lags the server as well as the client. @Firebrand1 can be seen with his physics desynced after changing the stiffness of a constraint, on his screen he was standing but on my screen, I was able to push him over and he stayed fallen over: SpringConstraint bugs - YouTube

Terrain disappears after changing stiffness.
image

I was not able to consistently reproduce the teleport to (0,0,0) and couldn’t get a proper recording of the behaviour.

Samples

SpringConstraint.FreeLength = math.huge
SpringConstraint.Damping = math.huge
SpringConstraint.Stiffness = math.huge
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Thanks for the report! We’ll follow up when we have an update for you.