It sort of looks to me like some of them are human-created (or at least human-curated), and some of the crappier or more nonsensical ones are created by generative AI.
I couldn’t find any ones that it would refuse to do – maybe it’s recently started using an AI image generator for those ones?
Edit: Okay, now I am sure that it’s using generative AI. I’m not trying to talk smack about the majority of them that are pretty reasonable and even sometimes creative, but also, sunset + butterfly yields:
It seems like you and maybe at least one other person are just not grasping what I am saying here.
A human did not make that decision. Sounds like it’s possible that maybe you are reading a lie that Google is telling you, and believing it is truth, I don’t really know, but yes they’re using generative AI for at least some of them.