Issue description:
I found a skeleton spawner in my hardcore world (seed -1307539905) and converted it into an experience and loot farm. However, the skeletons do not drop anything except arrows and bones, even while my sword has looting 3 on it. I used the same seed and created a survival world with commands enabled, and I found that the issue persists in survival and creative mode (still on hard difficulty).

This seems to also affect other mobs outside of skeletons. I have noticed it with pillagers in this world. I assume it affects other mobs too.

Since noticing this I have also tried it out on a new single player world with default seed and difficulty settings and have noticed the same problem. This affects drowned holding tridents too. I am unsure how the drop mechanics work with mobs, but this has made me wonder if it will be an issue with other mobs that rarely drop items outside of tools and armor— things like wither skeletons dropping wither skeleton skulls.

Steps to Reproduce:

1. Create single player world on version 1.21.4 with hard difficulty and seed -1307539905
2. Kill mobs with armor and tools and observe drops
3. Create single player world on version 1.21.4— random default seed and normal difficulty
4. Kill mobs with armor and tools and observe drops