The recent WWDC Apple launched "App Tracking Transparency framework" and will be a part of iOS 14.3:
With iOS 14, iPadOS 14, and tvOS 14, you will need to receive the user’s permission through the AppTrackingTransparency framework to track them or access their device’s advertising identifier. Tracking refers to the act of linking user or device data collected from your app with user or device data collected from other companies’ apps, websites, or offline properties for targeted advertising or advertising
It's very vague information from Apple and Google how App Tracking Transparency will handle Google Analytics. Anyone know if ATT will affect the usage of Google Analytics in iOS14?