Using an OnLook event causes jitter (sometimes)

Hey, I'm using Unity 2020.1 but have also tried this in 2019. I have setup input actions and a basic player controller.



It feeds the input events to the PlayerController.
In the player controller I just have some simple camera control

Code (CSharp):

1.  var delta = context.ReadValue<Vector2>();
2.  
3. var playerRotation = gameObject.transform.eulerAngles;
4. var cameraRotation = m_camera.transform.eulerAngles;
5.  
6. playerRotation.y += delta.x * Time.deltaTime * 10.0f;
7. cameraRotation.x -= delta.y * Time.deltaTime * 10.0f;
8. cameraRotation.y = playerRotation.y;
9.  
10. gameObject.transform.eulerAngles = playerRotation;
11. m_camera.transform.eulerAngles = cameraRotation;

Now this works(ish). Sometimes this is flawless; completely smooth. Other times when I enter play mode I get this terrible stutter between updates, rotation my camera upwards of 20 degrees between frames. Any reason this would happen with the above logic?

*EDIT
I've also put this into the update method and switched to using current mouse. It's slightly less noticeable but I'm still having stutter issues