As in case you don't familiar with what is "Sideloading", you should know it now. Sideloading means installing an APK application package into your Android device from other sources such as websites or third-party stores rather than installing from Google Play. Google allows users to install the APK file by giving an option of "Unknown Sources" in Android's security setting. Though, soon Google’s Advanced Protection Program will be an initiative to strengthen security.
Google’s Advanced Protection Program is designed with a broader set of safeguards to protect users from any targeted attacks or unnecessary risks. Users must use security keys for hardware and surrender some flexibility for the security level.
APK Insight has recently delved into the latest version of the Play Store 17.8.14 and includes a number of references to the blocking feature of the app. The Play Store will return the notification when you try to install an app with this feature enabled.
<string name="advanced_protection_dialog_title">App blocked by Advanced Protection</string>
<string name="advanced_protection_dialog_message">For additional security, Advanced Protection won’t allow apps from outside the Google Play Store.</string>
Advanced Protection further indicates that it would need APKs to be tested by scanning before being sideloaded on an Android device.
Now, before you start calling Google to shut down the one feature that makes it the preferred choice for many people, the restriction will not impact specifically how Android functions. The company is just trying to make the app safer for users who opt-in to additional security measures bundled with the Advanced Protection Program.
Malware and spyware are rising, this makes Google pay more attention and will protect users against random apps or malware that slip through apps installed outside the Play Store on your device. If you are opt-in, the new feature will check the APK for additional security before sideloading the device or blocking the APK installed on your Android device.