Side-loading is a long-standing method to get apps from alternative sources on Android devices, rooted or otherwise. Now, however, Google has decided to block this in phones linked to accounts enrolled in Advanced Protection. This is a program offering heightened security for potentially vulnerable users such as those involved in the media, corporate affairs or political campaigns.
Google's latest statement on Advanced Protection also introduces the move to have Play Protect app-scanning enabled by default within this framework. This feature is now estimated to scan approximately 100 billion apps per day for malware.
Therefore, these 2 new measures may keep personal or business accounts and their info safe. Then again, Advanced Protection users can still add non-Play Store apps so long as this is either done via ADB or proprietary app stores.