It's not even remotely the same thing as "can recite whole Harry Potter." If you ask an LLM to regurgitate Harry Potter it won't be able to do so because that's not how they work. They're prediction engines and it just so happens that Harry Potter quotes/excerpts are so pervasive on the Internet that the LLMs ingress ranks that style of wording higher than other styles.
Ask it to regurgitate some other, less-popular work. Do it for hundreds or thousands of them. You'll quickly find that those two examples you gave are the exceptions and that LLMs can't pull it off. They won't even get close.
unpack, unless you are going to convince me LLMs are predicting '0x5f3759df' :). Lossy compression is still compression.