@arstechnica copyright law has a "brain copy" exception https://www.gov.uk/government/consultations/artificial-intelligence-and-intellectual-property-call-for-views/artificial-intelligence-call-for-views-copyright-and-related-rights otherwise even just listening to a song would be illegal. I thought Facebook could argue AI is also a brain, but it seems the law has since been amended and explicitly states that while AI can also store copyrighted stuff in their memory, they can't legally reproduce it