What is the AppTrackingTransparency (ATT) framework?
The AppTrackingTransparency (ATT) framework is Apple’s IDFA opt-in mechanism introduced with iOS 14. This mechanism requests user authorization to access app-related data. Permission must be granted to track the device.
When will Apple enforce the AppTrackingTransparency (ATT) framework?
Per Apple’s January 27th, 2021 press release, ATT enforcement will be rolling out with their next iOS 14 beta release with broad enforcement in early Spring. Given that iOS 14.4 is already out, it will likely be iOS 14.5 that sees ATT enforcement.