After the photosensitivity fix, elytra particles are made to spawn on the respective hand which ignited the firework instead of in front of your screen. However if you duel wield fireworks, your right hand will do the igniting (according to the animation) but particles summoned on the off hand.
- Equip an Elytra
- Get some firework rockets
- Duel Wield them
- fly and use the firework rockets
The particles appeared at the wrong spot
The particles would appear where the firework is being used