also, at first I thought that could be the Weathered Mask, but the fact that the circle is tilted upwards proves that it’s Godseeker’s. I think that the video takes place AFTER the P5 ending (WITHOUT the flower), as Godseeker seems to be completely overtaken by the Shade Lord / God of Gods / Void Entity, as Void Tendrils burst out of Godseeker’s physical body (in Hallownest) at the end of the ending, and this could be the Shade Lord coming out of Godhome and extending itself into Hallownest, allowing it to inhabit Godseeker’s mask after destroying the rest of her physical form.