I see something similar when I am in sports mode also. I have not seen it in P mode at all. Here is what mine looks like.
Yours seems more like abrupt changes in the movement of the Mavic that the gimbal can't compensate for, which I would assume is normal, although I never saw such drastic movement in my gimbal even when flying erratically in sport mode. Mine only happens when traveling at full speed going straight forward and the vibration is very rapid.