Thanks TakeHomeTheCup, I switched PiP Quality to Ultra in Video settings and I immediately have a good quality (no distance fog) but when drone turret is at 1000m from target the PiP view starts to have more distance fog than the drone turret. It looks like there is still a difference between the viewdistance of drone turret and the viewdistance of PiP camera (at least around 1000m).
So can these 2 viewdistances be made the same for drone turret and PiP view?