Joints broke after last merge

After last commits joints do not connect bodies properly. It is easily visible in the Brax Basics Collab:
https://colab.research.google.com/github/google/brax/blob/main/notebooks/basics.ipynb
For example, in the last part actuators do not raise the ball to the target angles. Our codes using Brax also stopped working.
It looks like the code is reinvented right now, so I was wondering what is the vision of new joints.