Apple introduced App Tracking Transparency four years ago: Here's how it's going - 9to5Mac
This new feature would require third party apps to ask for user permission to track across apps before they'd gain access to your advertising ID (IDFA).
France fines Apple 150M for "excessive" pop-ups that let users reject tracking
Apple's App Tracking Transparency (ATT) poses challenges for smaller publishers by requiring double user consent for third-party tracking compared to single consent for its own data collection.