The bug consists of the number of arrows shown on the hot bar going down, when in reality it doesn't change. While you have a bow in your right hand, start the arrow animation and before the arrow fires switch to a different hot bar slot using the number keys on the keyboard. If executed correctly, no arrow is fired, but the number of arrows goes down.

To reproduce

1. Switch into Survival mode
2. Have arrows and a bow in your hotbar
3. Draw the bow
4. While letting go of the right mouse button, also press a hotkey to switch to a different slot
   → No arrow will be fired, but the arrow count decreases

When updating the arrow slot, the number will update to the previous one again.