It seems that the gameplay camera rotation returned by GET_GAMEPLAY_CAM_ROT is relative to the vehicle's rotation when in first person. It's similar to how some old flight sims behaved with mouse controls... you'd move your mouse cursor to some point on the screen and your ship would "chase" the cursor. In this case, we are at a disadvantage because we have no cursor that can be used as a reference to manually adjust your vehicle's heading.

I've tried clamping the rate at which the vehicle's heading changes with some success, so it doesn't yeet you around at 5,000,000RPM, but it still feels super floaty and generally unpleasant.

I think we should just disable this feature when in first-person mode.