As you've probably seen or heard Dropsitenews has published a list (from a Meta whistleblower) of "the roughly 100,000 top websites and content delivery network addresses scraped to train Meta's proprietary AI models" -- including quite a few fedi sites. Meta denies everything of course, but they routinely lie through their teeth so who knows. In any case, whether the specific details in the report are accurate, it's certainly a threat worth thinking about.