The bug
Creepers do not drop 100% of the blocks they break when exploding, unlike the TNT since the 1.14.
How to reproduce
Blow up a Creeper and see how many blocks you collect
Do the same thing with a TNT
Linked issues
is duplicated by 2
Comments 3
Definitely intentional
All explosions are extensions of the same exact behavior. If they were all meant to have 100% drop chances, it would have just been hard-coded into the base behavior and wouldn't have been affected by it's source - a bug like this wouldn't even be possible.
Probably intended.