I was playing around with snowballs, nothing too unusual but then I realised that the snowballs went through the creepers I was trying to hit. I played around with the issue and discovered that if the distance between the player and the target is below 2 blocks, the snowballs will pass through. I have attached two short clips of my experimenting for clear visuals.
(NOTE: The issue affects all other mobs too, except ghasts and the ender dragon.)

What I expected to happen:
The snowball would hit the target, no matter the distance I am from it.

What actually happened:

The snowball flies through the target and hits the block/unlucky mob that is placed behind the target.

Steps to Reproduce:

1. Find/Spawn in a mob.
2. Place yourself close to the mob
3. Throw snowball(s) at the mob.