If, when climbing a ladder, you sneak and stop then while holding the sneak key, you press the key in the direction of the ladder, while still holding sneak, and then pressing the key that makes you go in the opposite direction of the ladder, still holding sneak, you will float a little bit from the ladder. I don't know if it's a bug or it's supposed to be like that. Hope it helps anyways.

THIS IS A MISTAKE. THIS WAS NOT A CORRECT ASSUMPTION. THIS IS NOT A BUG. SORRY!