Minecraft version: 1.20.1
Modloader: Arclight
Arclight version: 1.20.1 (1061 - 47.2.0)
Environment: Multiplayer

Mod name: Configurable Extra Mob Drops
Mod version: 1.20.1-3.0

I've come to find custom drop data for humanoids such as villagers, pillagers and piglins doesn't work. I've tested this on a freshly created server with only Collective 1.20.1-6.66 and your mod installed.
The custom drops work for every non-humanoid mob without issues. I've also noticed that Witches and Vindicators' custom drop settings work more often but also not always.
This was all tested with a single item added to their loot table at a 100% drop rate.