Facebook's trackers (predominantly) link back deterministically to a logged in Facebook account. Your account on Facebook is linked to a list of known devices/b

Facebook's trackers (predominantly) link back deterministically to a logged in Facebook account. Your account on Facebook is linked to a list of known devices/browsers that you use (verifiable as when you try to log in to a device or browser that you don't use regularly, Facebook will prompt you). Facebook and Google will make use of probabilistic device fingerprinting techniques etc, but to nowhere near the same extent that a company would that didn't have FB/Google's level of logged in data.