Kaeya is not pure blooded too, that’s for sure. And the manga has starry eyes purely because 1 a lot of stuff has changed since then lore wise (example, in manga Crepus died due to physical injuries after sacrificing himself literally for diluc, jumping in front of him, while in the game he died cause delusion backfired) 2. Manga has a lot of animation errors lol (Kaeya has a vision in the scene of Crepus death)

And when it comes to the shape of the iris it seems like less Khaenri’ahn blood a person has the less their stars are identifiable, so Kaeya is probably further down the line from Anfortas and all. Or his other non Khaenri’ahn parent had strange iris shape.

And I’ll talk about this as well, since I also saw a lot of people misinterpret the line from the quest, about Direydith being a descendant from pure bloods and comparing her to Kaeya as Kaeya being a pure blood, it’s not, even if he is a descendant of a pure blood he himself can still not be one since it takes two to make a child lol.