The bug

If you instamine just one block that does not normally break instantly, it (rarely) makes no sound or makes the wrong sound (such as a breaking progress sound rather than the completed breaking sound). It happens very inconsistently but it only happens when you instamine just one block and it doesn't happen for blocks like TNT, slime blocks, honey blocks, grass, etc. I've only ever noticed it when using a shovel.

Update: One condition that seems to strongly increase the likelihood of making it occur is by jumping, and then, the instant you land, breaking a block, it does it more often. However, I have seen it happen when I am not jumping as well.

My sound IS on in the video, and if you turn it up loud enough, you can hear it makes a digging sound like you are trying to break the grass block, but not like you finished breaking it.

Steps to reproduce

1. Obtain an Efficiency III Netherite Shovel
2. Jump
3. Instamine a grass block right after you hit the ground
4. Repeat until the sound doesn't play / incorrect sound plays