The flight information on FlightRadar24 shows no sign of deviation or trouble, then abruptly ends during the ascent. https://www.flightradar24.com/blog/ukrainian-flight-ps752-cr...

That means the transponder became non-viable at that point. Any sort of in-air catastrophe could have caused that, including onboard fire.

Redundant airplane systems protect against component failure, but they tend to still be near each other. For example, if an AA gun were to tag the plane in the right place it could easily take out power to both a primary and backup.

It really doesn't look like a mid-air explosion. It was either a massive spontaneous fire for some reason (assuming the burning thing in the social media post was the plane) or it got shot down.

Looks like it got shot down, it just wasn't destroyed right away. Now there's even a video of the event.

https://twitter.com/trbrtc/status/1215348488164298752

That doesn't mean it exploded mid-air. If it exploded mid-air where the FlightRadar24 data end, the debris field would be in the direction of the flight and spread wide. Debris field is in the opposite direction and elsewhere though.

It was not that high, so the area is smaller than it would have been if the plane would have fallen from 10000 km altitude.