Ukraine

Can that specific plane even go near that fast without descending? The data may not be accurate, 900 mph in level flight is tough for a jet that size. Even at altitude.

It's possible the altitude is no longer accurate at the point on the speed graph that looks like a stall. But it's also possible the speed graph is no longer accurate at some point. If they are both accurate, the data doesn't make sense. It's most likely that at the point of the stall where it hit 33k feet, since the altimeter never changes again despite the wild fluctuations in speed after, it stopped accurately being read.

Maybe some electronics gave out at that point.