: Older tools like Apktool have had releases in the 2.x.x range (such as v2.0.2 ) that added support for newer Android versions like Marshmallow. APK signature scheme v2 | Android Open Source Project
: This update for Xiaomi devices (often labeled version 2.2.0-2-241230 ) is designed to optimize core security components and System features for Android 11 and above.
: This is a whole-file signature scheme developed by Google that increases verification speed and strengthens integrity guarantees by detecting changes to protected parts of an APK. It was famously integrated into Android Studio 2.2 to streamline packaging.
While there isn't one single "APK v2.2.0" that applies to all apps, several popular Android system components and tools have recently released versions matching that number. Notable Apps with v2.2.0 Updates