Here is a bug from an older invalid issue:

When when you swing with your arm in the air and don't hit anything, the sound of hitting a mob/animal will play.

(I don't know if this intentional, since on the Minecraft Java Edition you will hear nothing at all).

Response by Auldrick:  The swing-and-miss sound seems to have changed recently. I'm not sure how, because I never paid that much attention to it, but I've been noticing it. It wasn't mentioned in any recent changelogs, so it could definitely be a bug.