I've seen some other stuff recently that suggests the other inner planets like Mars and Mercury have slightly unexpected composition, like Earth and the moon. This has led to speculation that there was potentially a "billiard ball era" where chunks of protoplanets were smashing into each other, distributing heavier elements more evenly across the inner planets, and explaining the traces here and there that don't line up with Theia. A rogue body like a pluto- sized comet passing through and impacting one protoplanetary mass could lead to a whole series of impacts. There's still a ton of theories about the asteroid belt, and a bunch of new studies on the composition of the larger bodies in it. Exciting stuff!