Steps to reproduce:
1. Create new project (Or just open attached one and enter play mode)
2. Create 2 Articulation bodies, make one a child of the other
3. Set parent AB to be immovable
4. Set child AB to be prismatic joint on the vertical axis
5. Set child AB to have stiffness of 50 and a force limit of 2
6. Enter play mode
Expected: The force limit of 2 is not enough to hold the body aloft, so child AB should fall towards the direction of gravity
Actual: The force limit of 2 is enough to hold the body, proving that it is actually using impulses (when divided by Time.deltaTime, effectively making the force limit equal to 100)
Reproduced on: 2021.2.0b1, 2021.1.12f1, 2020.3.13f1