[reza_1999]

They bluntly say their notebook product is not private https://www.reddit.com/r/google/comments/1d7g3tu/notebooklm_... even for non-AI generated stuff like your notes and uploads.

[wolpoli]

While it says that your personal data may be seen by human reviewers to troubleshoot, address abused or make improvement based on your feedback, it does not mention that your data will be used to generate ideas for blog posts.