He probably used aphe

My best guess is that the fuzw sensitivity is 10mm 9f steel

No decoration that can be shot through has this level of durability

it most likely nicked something that caused the shell's fuse to activate...my best guess

You hit the dead panther and were shown the resulting shrapnel hitting the T-34. Volumetric hasn't been kind to 120mm+.

https://www.youtube.com/watch?v=40ydU3Z8WA8

Well show us a replay or it didn't happen. If you are playing on ULQ some physical walls/rocks will appear transparent and that's the only thing I can think of without some example I can look at.

Can someone explain how today shells are suddenly exploding 5-10 feet away when i shoot them at enemies? I shoot a T-34-57 (im in an IS-2) from about 40 feet away and before the shell can hit him, it explodes mid air. Is this a form of cheats or something? Wasnt just me either, my mate couldnt hit enemies either, because the shell just explodes and the shrapnel dinks off their hull
Edit: Clip here https://www.youtube.com/watch?v=40ydU3Z8WA8

Premature exploding shells