For whatever forked reason, increasing the Inertia Tensor Scale worked in stabilizing skeletal meshes when simulating over physx.
You can try and see if there is a similar Chaos option of some sort.
Realistically, that’s never been what the Tensor Scale is supposed to be for, so keep it in mind.
It’s normal to have to fine-tune anymdynamics, Phat, or other things between engine versions. That’s why normally you don’t change engine version on an active project unless you really know what you are doing.
You may also be able or have to drive the animation via control rig if you need specific behavior when at the end of a limb.
Simulation Space should be what the values are calculated in. World or Local (mesh space) should both work.