After the 1.19.20 update, using a charged firework rocket, or one with a pattern added to it, doesn't damage the player while flying. i found out thid bug when i accidentally used a charged rocket, and it did no damage to me. 

How to replicate:

1. Change game to survival
2. Use any type of firework rocket (example: small ball, red)
3.  Equip elytra
4. Launch with the rocket