The bug

The view moves forwards when moving upwards, for example by flying up, backwards when moving downwards, for example by falling. Since the player head is not moving at all I do not expect the view to change either.

How to reproduce

1. Change your gamemode to Creative
2. Place a single slime block
3. Stand on it
4. Face straight down and start flying upwards for at least 50 blocks
5. Start falling
   → The crosshair is in front of the slime block when bouncing up and behind it when falling down