Beendare knows. 1.5” @ 40 means your arrow is not achieving perfect flight. Impacting fairly close to your point of aim is not the issue. It’s that your arrow is not flying straight and true, So it’s not grouping as well as it could, is more susceptible to bad inputs from the bow (hand torque), planing, and when it hits an animal it may actually be at a slight angle relative to the flight path (yaw) and it can lose a bunch of energy, affecting penetration …
With a minute adjustment to your rest, like 1/32-1/64 you could have perfect flight and eliminate all
that.