The Bug:
Goat's long jump is not affected by the jump boost effect.
Steps to Reproduce:
Build a line of blocks in the air, with a powder snow block in the middle.
Alter the goat's data through the use of the following command, so that it performs a long jump:
/execute as @e[type=minecraft:goat,limit=1,sort=nearest] run data modify entity @s Brain.memories."minecraft:long_jump_cooling_down".value set value 1
→ ✔ Notice how the goat performs a long jump. Take note of how high it jumps.
Effect the goat with jump boost through the use of the following command:
/effect give @e[type=goat,limit=1,sort=nearest] minecraft:jump_boost 100 3
Alter the goat's data once again through the use of the following command, so that it performs a long jump:
/execute as @e[type=minecraft:goat,limit=1,sort=nearest] run data modify entity @s Brain.memories."minecraft:long_jump_cooling_down".value set value 1
→ ❌ Notice how the goat did not jump any higher than it previously did, despite having the jump boost effect active.
This issue has been fixed in 1.17.1 Pre-release 1.