She has two buffs active on her. No one else in the party has these auras

The active abilities are.

Lathander's light.

Demonspirit Aura.

I looked both these up and don't see any direct translations in current stuff. But it sounds a lot like the abilities the old Morninglord class used to have

Then remember that Shadowheart has those strange glowing spells she cant controll

Its still possible these are gear related, but between this and how Swen remembered he was about to spoil something and stopped playing quickly, it makes me think maybe Larian accidentally leaked Shadowheart's story.