It depends on what you are looking for. Identifying AI generated data is generally hard, though it can be done in specific cases. There is no mathematical difference between the 1s and 0s that encoded AI generated data and any other data. Which is why these model collapse ideas are just fantasy. There is nothing magical about any data that makes it “poisonous” to AI. The kernel of truth behind these ideas is not likely to matter in practice.
No. I simply don’t see a plausible scenario for that. The social media comments are quite deplorable. You really have to look for bubbles with educated people. I don’t know why this gets so much traction. Maybe it’s because the copyright industry likes it, or maybe it feeds some psychological need like Intelligent Design.