I don't know. Perhaps because it is not necessary to have android:exported='true' declared for Android 11. Note Anke's " because android:exported="true"
is not declared in the Manifest with the extensions used.
Any tip/hint if extension developers need to take care of this" in Androids lower than 12. "
It appears the third party developer's extension does not declare android:exported='true'.
MIT's older Companion might have provided the required manifest and the most recent Companion might not
Every APK file includes a target SDK specification and newer versions of Android (generally) try to respect the rules of the target SDK specified. Your app built in May 2021 would have target SDK 28 or SDK 30 most likely, but your app built today will target SDK 31. Therefore, extensions that followed the SDK 28 or 30 rules will not work when the app is recompiled to target SDK 31. You will need an updated copy of the extension that follows the new rules.
Google Play Store is implementing additional changes going forward as well that apps that target at least 2 years back will no longer show up for newer Android versions. Hopefully they won't enforce this on Android users as a whole as well.
