the pilot better turns on ADSB if he does not want to collide with other planes. usually they send an ID with no other information, but if that ID is known… lemmy knows
I'm not saying that Putin is aboard the plane, but I don't think that Wagner has any substantial air-to-air capability. I know that they operated some ground attack planes in Ukraine earlier, but AFAIK, that's it. So there probably is limited risk to Putin in that information going out.
EDIT: Apparently it turned off its transponder later while in flight.