Android currently supports uninstalling updates to a certain app, but only for system applications. Also, it's usually only a temporary measure, as the Play Store will eventually check for updates once again and restore the latest version. Android Q might allow users to revert any app to an earlier version, if deconstructed code from a leaked Android Q build is to be believed.

XDA Developers found a few strings and new features in Android Q that point to support for downgrading applications. Two new permissions for system-level applications, "PACKAGE_ROLLBACK_AGENT" and "MANAGE_ROLLBACKS," would presumably allow the Play Store to rollback an app to a previous version. There are also two new broadcast events, "PACKAGE_ENABLE_ROLLBACK" and "PACKAGE_ROLLBACK EXECUTED," which could allow apps to figure out if they have been reverted to an older version and behave accordingly.

<protected-broadcast android:name="android.intent.action.PACKAGE_ENABLE_ROLLBACK"/>
<protected-broadcast android:name="android.intent.action.PACKAGE_ROLLBACK_EXECUTED"/>
<permission android:name="android.permission.PACKAGE_ROLLBACK_AGENT" android:protectionLevel="signature"/>
<permission android:name="android.permission.MANAGE_ROLLBACKS" android:protectionLevel="installer|signature"/>

Finally, a new "--enable-rollback" flag has been added to Android's "pm" command (commonly used through ADB). It didn't appear to do anything in the leaked Android Q build.

It's interesting to see Google support some level of reverting app updates, after many years of completely ignoring the possibility. There's also a chance the regular Play Store won't expose this functionality at all, and it will be limited to niche use cases (like reverting faulty updates on Android Things IoT devices).