Wow ... so the photographer chose to put the horizon in the center of the frame. That’s impressive.
Not.
You know nothing of the angle between the camera and the gravitational vector.
Because you weren’t there. You apparently want to believe the camera was aimed perpendicular to gravity, for whatever reason. But you don’t know.
Thing is, you can’t BS me ... I’ve been at high altitude, and I don’t mean in a commercial airliner. Your entire argument is based on a false premise, that the horizon is seen center of FOV by looking perpendicular to gravity.
Until you abandon that false premise, you’re just making noise.
Have a nice day.
That makes no sense. You can't SEE gravity.