If you sneak while gliding with the Elytra, your camera position changes to a non-gliding player's camera position.
What I expected to happen was...
The camera position wouldn't change, or at least would change but won't change into a non-gliding player's.
What actually happened was...
The camera position changed to a non-gliding sneaking player's.
Steps to reproduce:
1. Equip the Elytra.
2. Start gliding.
3. (Optional) Go into F5 mode.
4. Sneak while gliding in midair.
5. Observe the camera position moving upwards.