Something Seems to Be Wrong Here...

It goes past the minion and hits the edge of vayne's hitbox, also probably slightly different serverside due to ping. The hook snaps to the center of the hitbox, making it look like it went through the minion.

Trick shots are a sign of a good thresh player (or just dumb luck).

That is about right, and by right I mean as bs as 's hook hitbox and spaghetti coding

Hahaha, ahh spaghetti code never fails to let us down...

This is normal. Been happening for years. If you looked at the actual hitboxes it would make sense, but your camera angle makes it look deceptive.