It's hard to tell if they changed the hitbox or reduced the projectile size of the arrow.
It looks like hitboxes are better, more conformed to the model.
I'm happy either way (realistically to be the most happy would be if they fixed both, but I'll take what I can get). No longer will tree trunk hanzo be getting free kills while I'm behind cover cause he shoots a wall. Now you'll have to actually , you know aim, to get a kill rather than in the general direction shoot an arrow