tons of errors simmilar to:
Failed to execute LootRule minecraft:leather_helmet/common/STAT/0.25!
it causes the helmet to generate but without any enchants or affixes,

Game version: 1.18.2
Forge ver: 40.2.17
Mod version: 5.8.1
Modpack: Downcraft 2.0.14

This happens if too many affixes are removed from the pool, which is likely a modpack configuration issue.