The bug

As in the title.
Even if they are holding a wooden shovel and you give a diamond shovel, they will never pick it up. However, they will can pick up a wooden sword.

How to reproduce

1. Use the following command

   /summon husk ~ ~ ~ {CanPickUpLoot:1b,HandItems:[{id:"iron_shovel",Count:1b},{}]}
   

2. Set the mobGriefing gamerule to true if it is not already

   /gamerule mobGriefing true
   

3. Throw a diamond shovel at the husk
   → It won't pick it up
4. Throw a wooden sword at it
   → It picks it up despite the sword being weaker (4 attack damage) than the iron shovel (4.5 attack damage)