From Flickr (Now owned by Oath). I had no idea, never was a big Flickr user, but now I never will be. Holy crap.
(From their Privacy Policy): This includes: analyzing content and information when you use our services (including emails, instant messages, posts, photos, attachments, and other communications), linking your activity on other sites and apps with information we have about you, and providing anonymized and/or aggregated reports to other parties regarding user trends.