According to subscribers suing, AMC allegedly installed tracking technologies—including the Meta Pixel, the X Tracking Pixel, and Google Tracking Technology—on its website, allowing their personally identifying information to be connected with their viewing history.
Some trackers, like the Meta Pixel, required AMC to choose what kind of activity can be tracked, and subscribers claimed that AMC had willingly opted into sharing video names and URLs with Meta, along with a Facebook ID. “Anyone” could use the Facebook ID, subscribers said, to identify the AMC subscribers “simply by entering https://www.facebook.com/[unencrypted FID]/” into a browser.
X’s ID could similarly be de-anonymized, subscribers alleged, by using tweeterid.com.
Or, just don’t have those IDs by not having accounts. Nobody’s identifying me by my Facebook ID if I don’t have one. Simples
Problem is that even those that have never setup an account with Facebook still have a profile that Facebook built on their behalf. If you are in any photos that friends/family/coworkers uploaded and if even one person named you in the photo, you are now known by fb and anyone who uses that data.