The bug

Pillagers in raids (Bad omen level 5) can commonly spawn with crossbows enchanted with multishot/quick charge in all waves except for wave 1-3 while piercing and unbreaking can very rarely spawn in raids.

How to Reproduce:

1. Start a Creative world
2. Set your difficulty to hard
3. Run

 /effect give @p bad_omen 30 5 

4. Run

 /give @p diamond_sword{Enchantments:[
{id:looting,lvl:150}]} 

5. Run the /locate command and teleport to the nearest village
6. Kill all pillagers
7. Collect their enchanted crossbows
➡ Observe that they always have Multishot or Quick Charge, and very rarely Piercing or Unbreaking.