There’s a problem when change timeScale only.
I fixed that with my narrow understand.
You can reference my changes screenshot to fix this issue clearly.
Hmm. When you slow down the game by Time.timeScale, rigibodies will indeed frame jump since they are updated in a different framerate (ProjectSettings/Time/FixedTimeStep).
One way, is to set the interpolation mode on the Rigidbody component inspector to either “Interpolate” or “Extrapolate” instead of “None”.
Would that resolve the issue in your case?