Security Guard Service
com.miui.greenguard
The app includes three different antivirus brands built in that the user can choose from to keep their phone protected: Avast, AVL, and Tencent.
Upon selecting the app, the user selects one of these providers as the default Anti-Virus engine to scan the device.
It the app that scans an app before installing it
NOTE: A vulnerability was found in 2019