If an allay has items in its inventory, and the game is exited and reloaded or the entity is unloaded (e.g. due to distance) and reloaded, the items in the allay's inventory are lost.

This is due to a change in 22w42a, class net.minecraft.world.entity.animal.allay.Allay, method readAdditionalSaveData:

-        this.inventory.fromTag(compoundTag.getList("Inventory", 10));
+        if (compoundTag.contains("Inventory", 10)) {
+            this.inventory.fromTag(compoundTag.getList("Inventory", 10));
+        }

The "Inventory" tag is a List, which is type 9. So the added check for contains("Inventory", 10) will never succeed.

The same error was made in net.minecraft.world.entity.monster.piglin.Piglin and net.minecraft.world.entity.npc.AbstractVillager.

P.S. This is the same type of error that's causing MC-198493.