When I set up the gimbal with my iPhone 11 Pro, everytime my phone is not horizontally leveled by a couple of degrees.
I checked everything, phone clamp is in the middle, magnet is properly attached to gimbal etc. Or is it normal that I have to set Horizontal Gimbal Adjustment every time when I start it up?

Hi there. Thank you for reaching out and we're sorry for the trouble. Can you please try to perform the gimbal auto-calibration to see if the issue persists? In addition, could you please send us a short video or image showing the issue for us to check? Please keep us posted. Thank you.

If I do a auto-calibration, it fixes the issues. But a lot of times when I start up, my phone is not level, which is pretty annoying.

Does it make a difference without the phone case?

I don‘t have that problem with an iPhone 11 (non-Pro).