Stomach model shaking
Prey players frequently see the stomach model of their predator shaking. It appears to change position back and forth each frame, becoming offset one frame then reverting to its original position the next.
The mouth model however does not have this issue. As the mouth is attached to the player's camera whereas the stomach is attached to the local entity of the predator, it should be safe to assume this is caused by either attachment issues or the local player entity being inaccurately positioned.