"Tilt" is ambiguous, the drone tilts in two directions pitch-nose-up/down and roll-right/left.
In follow me the gimbal should attempt to keep the camera at the same pitch with respect to a horizontal plane and horizontal with respect to roll, i.e. it counters the pitch and roll of the drone.
In FPV mode the gimbal should attempt to keep the camera at the same pitch with respect to a horizontal plane BUT the gimbal will NOT attempt to keep the camera level with respect to roll, i.e. the camera will roll as the drone rolls but the gimbal should counter any change in the drone's pitch.