I run into this with melee attacks in a lot of first person games (Cyberpunk, Deep Rock Galactic). Often the camera is pinned to the character's head, the head which is animated during a melee attack. Both games above actually have screen shake accessibility sliders which critically do nothing to prevent this source of motion sickness.

I suspect it has to do with "camera movement I didn't control". I recall some research done by Valve during the VR development days that resulted in the "teleport" movement fix.