Where: Seems to be able to happen anywhere, had it three seperate times in three different locations- The mists, Harvest Temple, and the church in Ghastria.
When: Whenever Vision of the Omniscient Eye is cast on my character Sarade Avhoste, and if the theory is correct- Anyone else with Darkvision.
What: Casting Vision of the Omniscient Eye on Sarade gives her an aura of darkness visually, but without any mechanical effects attached, and everyone else can also see the darkness. The spell still prevents blindness correctly, although this bug makes it very difficult to see things in most places.
Recreate: Cast Vision of the Omniscient Eye on Sarade, or presumable, any character or npc that has darkvision.
Ideas: I think it's some odd interaction with darkvision, as before her most recent level up and gaining that, there were no issues with the spell that I noticed. I also talked to another player in game that mentioned the same bug occurred when casting the spell on a fairy familiar.
Screenshot below of the bug in action in the mists.