If you use a datapack to give the villagers a custom loot table (I wanted them to drop bells) they will also drop the item when converted into a zombie villager.

How to reproduce:
1) Download the linked data pack.
2) Spawn a villager next to a zombie and wait for the zombie to convert the villager.
3) Watch as bells drop even though the villager is not dead.

This bug should be removed as it is annoying in villager trading halls.