hello , I have a problem with slicing skinnedmesh , what happens is that one of the objects (neg/pos) starts to act very jittery and flies into the air. I cant find the problem but it seems that the hierarchy of bones and joints is not correct. it usually happens when I slice the character's legs but not always.
I share a screenshot here

Hi. Probably something with your ragdoll setup.
I could suggest you to try to setup a ragdoll using this asset:
Also check Unity's recommendations here: