Google has added its own security system for apps that are not downloaded from the Google Play called “Play Protect”. It is possible that the MobiSafer application is detected as potentially dangerous.
To prevent the app from being uninstalled, you must disable Google Play Protect and notifications related to Google Play Protect.
Open “Play Store” application => Tap on Menu button => Select “Play Protect” => Select “Settings icon” => Disable “Scan device for security threats“.