What is ios 16.4?

As of August 2021, there is no official release for iOS 16.4. The latest version available is iOS 14.7.1.

However, it is likely that Apple will release iOS 15 in the fall of 2021. iOS 15 will include new features such as FaceTime improvements, redesigned notifications, and updates to Maps, Safari, and Wallet.

It is unclear if Apple will release any other updates labeled as iOS 16.4 in the future.