You can walk off blocks without moving if you stop sneaking near an edge

The bug

If you sneak close to an edge, then release your sneak key, you will sometimes fall down. Happens significantly more commonly with Swift Sneak and Speed potion effect, but can rarely happen without either.

Steps to reproduce

1. Put on the Swift Sneak III leggings and use the Potion of Swiftness(Speed II).

2. Sneak close to the edge of the block.

3. Repeatedly release and click the Shift + W button.