Looks like a vid included on Military Summary Channel. They were saying it was either one of the UKR air defense missiles landing on the building or debris from a RUS missile that was destroyed by anti-missile fire. Hence, the fact it is a flaming object already.
o7
Found that corroborating vid from Military Summary Channel @ 4:10. Was apparently in Kiev.
https://m.youtube.com/watch?v=wvYBZs3LX-w