This has been obvious from the get-go. I guess a paper makes it official.

https://futurism.com/the-byte/google-researchers-paper-ai-internet

GOOGLE RESEARCHERS PUBLISH PAPER ABOUT HOW AI IS RUINING THE INTERNET

Google researchers have come out with a new paper that warns that generative AI is ruining vast swaths of the internet with fake content — which is painfully ironic because Google has been hard at work pushing the same technology to its enormous user base.

(Related) A real solution or simply kicking the can down the road?

https://www.makeuseof.com/ai-running-out-training-data-solutions/

AI Tools Are Running Out of Training Data, but There Are 6 Solutions