u/Curious_Summer5870

It was revealed in Special Operation quest, which is Part 2 of the Archon Quest Song of the Welkin Moon: Act III - A Nation That Doesn't Exist that Khaenri'ah's lack of sun led to people eating mushrooms and meat.

And Kaeya's speciality food is Fruity Skewers made exactly from that. I felt this was a nice touch to show us that we shouldn't forget where the Cavalry Captain's roots lie. And maybe, more of his interests and dialogues that we were taking lightly might have a deeper darker meaning.