Due to the openness of the Android system, users can install applications from unknown sources. However, installations of unknown source applications tend to be at higher risk. Google is aware of this, and Android 8.0 in 2017 has made it harder for users to install APK files downloaded from outside the store. The new Android Android Q is a step further in this regard, Android Q currently disables ‘Install unknown apps’ permission.
In Android 8.1 Oreo and Android 9 Pie, if a user wants to install an app from outside the Google Play store, they must turn on the “Install unknown apps” permission for the app where the APK is installed. Once the permission is turned on, it remains enabled until the user manually disables it.
This situation has changed in the beta version of Android Q. Every time a user installs an APK of unknown origin, the user needs to enable “Install unknown apps” permission. If users need to install a large number of apps from outside the store, they have to do a lot of clicks in Android Q.
This feature is currently only available in beta, and Google has not announced whether it will remain on the official version.
Source, Image: 9to5google