Arms of idling pillagers are always stationary/never moves

The bug

If you look close enough, you'll notice that the arms of an idling pillager never moves, unlike the arms of idling players and piglins.

How to reproduce

1. /summon pillager ~ ~ ~ {NoAI:1b}
   

   /summon piglin ~ ~ ~ {NoAI:1b}
   

2. Observe their arms
   → The piglin's arms move, but the pillager's arms don't