Dropsitenews published a list of websites Facebook uses to train its AI on. Multiple Lemmy instances are on the list as noticed by user BlueAEther
Hexbear is on there too. Also Facebook is very interested in people uploading their massive dongs to lemmynsfw.
Full article here.
Link to the full leaked list download: Meta leaked list pdf
Given that we used to see lots of Meta scraping a while back on our instance and had to implement Anubis as a result, it is interesting to see that slrpnk.net doesn't seem to be on this list (anymore).