Google will no longer provide Play Services APK updates to devices that are still on Android Jelly Bean from the end of August. Apk version number 21.30.99 will be the latest update for these smartphones. These are Android version numbers 4.1.x, 4.2.x, and 4.3.
In practice, the end of support means that smartphones with Jelly Bean will no longer receive updates for certain apps. Developers must then specifically build support for the older apk version in the app. If developers do not do this for their app, Jelly Bean smartphones will no longer be able to download and install new updates for that app.
Google says it will stop supporting Jelly Bean because a “very small percentage of users” are still on Jelly Bean. It would be less than one percent of all active Android smartphones. It would cost Google too much developer and QA time to provide this version with Play services updates any longer.
Android Jelly Bean appeared nine years ago and supports api levels 16, 17 and 18. After August, only api level 19 or higher will be supported, or Android version 4.4, also known as KitKat. Google last discontinued Play services support in 2018, then for Android 4.0 Ice Cream Sandwich.