How to reproduce:
1. Have 2 players join a server

2. Give 1 player an elytra and some fireworks (I tested with the 1 fly lenght fireworks)

3. Make a wall

4. Have the other player stand near the wall

5. Have the player with an elytra fly out of the other player's render distance

6. Have the player with an elytra come back spamming fireworks

7. Have the player with an elytra hit the wall

Expected Result: If player with an elytra does not die from the impact, he will get stopped next to the wall

Observed Result: The player with an elytra has their hitbox misplaced behind the wall and the other players are able to attack the person

Extra Comment: I tested this on a Paper server without any plugins. I also tested this on a Paper server with plugins. I also tested this on 2 different hosting services.