Skeleton arrows don't deal damage, if they shoot while underwater, and you are moving when the arrows hit

How to reproduce:

Spawn a skeleton underwater. Go to survival mode.

When you're out of water, the hostile skeleton will try to shoot you. However, I noticed when moving around left and right, that when the arrows do hit, they don't make any damage. They just ricochet back or drop to the ground.

However, if you stand still, then they do damage.