Sneaking allows players to move too far off the edge of a block

This is intentional, it allows you to safely extend a bridge over a dangerous precipice or build a scaffold for a large structure. You can walk the same distance over the edge without falling if you aren't sneaking, but if you are sneaking, it'll stop you before you drop too far off.

I experienced an issue once whereupon releasing the sneak key, my character moved slightly further and fell off the edge. That was probably due to a keyboard input error but in any case use this feature with caution!

The player hitbox is still touching the block, therefore the player is not falling.