I doubt it's OpenAI. Maaaybe somebody who sells to OpenAI, but probably not. I think they're big enough to do this mostly in-house and properly. Before AI only big players would want a scrape of the entire internet, they could write quality bots, cooperate, behave themselves, etc. Now every 3rd tier lab wants that data and a billion startups want to sell it, so it's a wild west of bad behavior and bad implementations. They do use residential IP sets as well.