As you can clearly see in this video, Pe-8 damage model works just fine. Just like Stalin intended. The mysterious explosion (I guess it was the bomb, I don’t think fuel can explode like that from 20mm hit, of course the bomb survived its own explosion, because it has a spall liner or something) harmlessly left the aircraft via blowout panels, and you can’t expect 20mm cannons or fire to destroy glorious Soviet design.
He only died because “plane burned out”, I guess it just got tired from cosplaying helicopter and wanted to take a day off. I also feel burned out after a hard day of work.
Is normal.
Here’s the link to the replay if you want to witness Pe-8 greatness (and other events) from other angles:
https://warthunder.com/en/tournament/replay/156348891319755895