Oh wait, some drones go dark when approached. That indicates evasion and concealment. Why?

Occam's razor: because all these "drones" are people mistaking airplanes, stars, and other ordinary objects in the night sky for drones. And sometimes - by sheer chance - these objects will pass behind a cloud shortly after being seen by a person. That won't happen often, but in a large enough population (now primed to "Watch the Skies!"), it will happen, and they will go on social media.

Far more likely than someone being advanced enough to design a drone with the technical capabilities to scan the entire field of vision of the ground and be able to tell when someone's eyeballs have shifted to look at them - at night! - and sense that and be able to react immediately to "conceal".....but too dumb to just not put lights on it in the first place!!!!

Seriously! If someone didn't want the drone to be seen, they wouldn't put lights on it in the first place!! Or they'd just keep them off! Or they just wouldn't have them face downward!!