On genuine DLs the face casts a shadow onto the background. The person was shot against a wall – and nobody cut the background out afterwards. That shadow sits on nearly every licence.
A clean background without a single shadow is a classic editing tell. Removed it out of tidiness – handed the file over.
The shadow agrees with the light on the face: same direction, same softness. It lives in the frame under shared physics.
The machine compares lighting on face and background. No shadow – no consistency. Shadow the wrong way – also a flag.
We give the background its physics back: direction, softness, density.
Cut the background to zero and got rejected? Send it – we'll put the shadow back.