Summary:
Unlike other projectiles, llama spit can damage withers which have half health or less.

Steps to reproduce:

1. /summon minecraft:wither ~ ~ ~ {NoAI:1b,Health:150}

2. Spawn a llama

3. /damage @e[type=minecraft:llama,limit=1,sort=nearest] 1 minecraft:mob_projectile by @e[type=minecraft:wither,limit=1]

4. /data get entity @e[type=minecraft:wither, limit=1]

Observed results:
The llama spit was able to damage the wither, which doesn't match other projectiles.

Expected results:
Llama spit shouldn't be able to damage the wither when it has half health or less.

Video:
0421(1).mp4