Report: iOS Users Who Opt-Out of App Tracking Continue to Be Tracked by Facebook and Snapchat - MacRumors

In May, Apple launched its App Tracking Transparency feature that allows users to opt-out of being tracked across apps and websites for advertising purposes.

The Financial Times said that Apple's position was the result of "an unacknowledged shift that lets companies follow a much looser interpretation of its controversial privacy policy." Apple has instructed developers that they "may not derive data from a device for the purpose of uniquely identifying it," which developers have interpreted to mean that they can still observe "signals" and behaviors from groups of users instead, enabling these groups to be shown tailored ads anyway.

Apple has not explicitly endorsed these techniques, but they allow third parties to track and analyze groups of users regardless of whether or not they have given consent to user-level tracking.

In June, Apple faced pressure to tighten the rules around App Tracking Transparency after it was found that third parties were using workarounds to identify users who do not consent to be tracked, but there have been no changes around looser "probabilistic" methods of user identification.