I really do not understand why the Autopilot when switching from FBWA to Auto put throttle to zero for a very short time and the to full throttle and a lot of pitch even if the altitude is very close 29,2 meters to the target altitude of Tecs_Hdem 30 meters.
The range finder readings at the beginning of Auto mode are not good because the plane rolls to go to next waypoint.
Nothing is wrong with Auto take off , I just prefer to take off manually or in FBWA , it is a way to check if the plane react correctly to commands, an old habit that came from years of multirotors tests.
In fact I never used till now auto take off.
The suggestion of using FBWB before switching to Auto solve the problem , the transition to Auto for throttle level is much more smooth , thanks !