Datapack Features - yiner233/Age-of-Exile-wiki GitHub Wiki
A feature being a datapack means that it can probably be modified in its entirety, entries removed or added.
This means that the feature can vary A LOT in between modpacks.
For example Unique gears are datapacks, and a modpack can add a bunch of them, or make them super rare or super common!
This is why you should ask for help in relation to these features on the modpack community's discord or place, or check the In-game Wiki if the entry type exists for it.