Comment by fuzzbazz
From a quick web search I can find that there are book review sites that allow users to enter and rate verbatim "quotes" from books. This one [1] contains ~2000 [2] portions of a sentence, a paragraph or several paragraphs of Harry Potter and the Sorcerer's Stone.
Could it be plausible that an LLM had ingested parts of the book via scrapping web pages like this and not the full copyrighted book and get results similar to those of the linked study?
[1] https://www.goodreads.com/work/quotes/4640799-harry-potter-a...
[2] ~30 portions x 68 pages
Meta has trained on LibGen so we don't really need to speculate.
https://www.wired.com/story/new-documents-unredacted-meta-co...