But the thing is the law has already established this with people and their memories. You might genuinely not realise you're plagiarising, but what matters is the similarity of the work produced.

ChatGPT has copied the data into its training database, then trained off that database, then it runs "independently" of that database - which is how they vaguely argue fair use under the research exemption.

However if ChatGPT can "remember" its training data and recompile significant portions of it in certain circumstances, then it must be guilty of plagiarism and copyright infringement.