Elytra's speed gain does not match the gravity attribute

When gliding with an Elytra, the player only gains horizontal speed if it is going downwards; regardless of how the minecraft:generic.gravity attribute is set.

Steps to Reproduce:

1. In Creative mode, fly away from the ground
2. Equip an Elytra
3. Run the command /attribute @s minecraft:generic.gravity base set -0.08
4. Activate Elytra glide

Observed Results:
The player remains stationary horizontally

Expected Results:
The player would gain horizontal speed according to their rotation and gravity

Screenshots/Videos:
Gravando 2024-04-20 125605.mp4

Notes:
To set your gravity attribute back to default, run the command /attribute @s minecraft:generic.gravity base set 0.08