The Sherman weights up to 38 Tons (depending on the model), the T34/85 up to 35 tons, the Comet 33 tons.
So this small difference makes the difference if you get heavy crush or not? I dont think so.
Besides, the Brummbär weights 28 tons !?!?!?
So the Panther weighs about 25% more than any other medium tank. Combined with its size and armor, it would be considered a heavy tank if it wasn't for the Germans calling it a medium.
I don't know why the Brummbär has it.