This bug is twofold: First of all, explosions in most materials are unusually uniform, whereas before they were more random in shape.
Secondly, End Stone seems to have the same blast resistance as stone.

For the stone tests, I used a 5x5x5 cube, and cut away the front layer after the explosion. As you can see in the screenshots, a perfect 3x3x3 cube was missing.
I used TNT in all tests.

Edit: Further testing of other materials revealed that the dirt's uniform crater was a fluke. When larger explosions were created, the other materials were less uniform as well.