Seb Joseph, Digiday:
And herein lies the rub for ad execs. Apple has told them fingerprinting is off-limits but doesn’t seem to be aggressively enforcing this policy. Few execs, however, believe this perceived inaction will last. Eventually, goes the thinking, Apple won’t need to enforce a policy like ATT to rid its mobile operating system of fingerprinting — it will have the technology to block it from ever happening in the first place. The reason: Private Relay.
Private Relay renders a person’s IP address useless for fingerprinting because it redirects web traffic through two separate servers. Granted, an IP address is just one of many aspects that make a fingerprint of someone’s behavior on a device — but it’s an important one.
For all of marketers’ thrashing and gnashing about App Tracking Transparency, it really is only a policy change. Apple certainly tries to enforce it; it knows about SDKs that function as trackers, and at least one attempt to circumvent these rules has faltered. iCloud Private Relay creates a much more robust barrier, especially if it is extended to all network traffic from all apps — and, notably, compliance does not depend on the attentiveness of an App Store reviewer.