Firework boosting on elytra continues in spectator mode

The bug

Switching to spectator mode after using a firework to propel elytra flight will not end the firework effect, causing particles to continue to spawn underneath the otherwise invisible player.

How to reproduce

1. Give yourself a firework with flight duration 50. (This can also be done with a flight duration of 3, which can be crafted with 3 gunpowder.)

   /give @s minecraft:firework_rocket[minecraft:fireworks={flight_duration:127}] 

2. Glide with an elytra, use the firework, and switch to spectator mode before touching the ground.
3. Notice that the firework particles are still spawning below you.
4. Have another account join the game. They will see firework particles coming out of a spectator.