It’d probably just your collisions snagging onto something.
This is very common with multiple parts in a chain.
Say character arm.
If you grab and pull from the hand bone, you normally go Mr. Fantastic - or Gumby. Whatever you prefer.
If you grab from the upper arm you get no stretching.
WITH PhisX, this is fixed by increasing the Inertia Tensor Scale progressively through the PHAT asset bones/colliders whatver they are called.
For a character arm, shoulder at 1, upper arm 1.5, lower arm 1.75, hand 2, on the relevant axis (default mannequin I think X) used to do it up until version .22
ALSO
Building a custom version of the engine with an updated physX code helps the initial problem.
I suggest doing both.