@Freznosis It’s not Cinemachine, it’s problems with the stability of Unity’s framerate. The reason it seems to go away when you turn the damping down is that with damping on, the car will jump in the frame, while with the damping off the background will move irregularly, and the car jittering in the frame is far more visible to us.
However, there is hope. This thread is all about irregular framerate, and Unity is taking it very seriously. There is an active effort being made to fix it.