No snow on top of the flashlight means it was placed there in recent days before the tent was found, with no snowfall in between.
It could also mean that sunlight that penetrated the snow a bit warmed up the dark material of the flashlight to melt the snow on it... Given the weather reports I looked at, days were quite short and most of them were cloudy at the time, so I don't think this explanation is viable.
So it was not a Dyatlov group member who placed the flashlight there.
I would also say that extensive snow cover on the tent, but not on the flashlight would mean that it also were not the "stagers" because even if the tent was staged by them, the flashlight must have been placed there much later after a snowstorm.
Or did they forget something and went back for it weeks later, perhaps at night?
I think we can also assume it was placed there at night, otherwise whoever left it there would realise their "mistake" and put it in the tent or put some snow on the flashlight.
Having said all this, imagine this incident happened today and a competent investigation is carried out, fingerprints are taken, and the person who last touched that flashlight is found. This still wouldn't link them to the incident... it is most likely someone who found the tent weeks later and may not even have taken anything, just looked in and then left their flashlight or one they found in the tent there... They probably didn't even know there were bodies down in the forest as they were under snow. So even if this piece of the puzzle is solved, I'm not sure it unravels the entire mystery.