According to Techcrunch, Apple has fixed the "this app is no longer shared with you" bug in iOS last week.
The bug in the Apple App Store last week saw a large number of duplicate app updates that made some apps unavailable and some apps would not launch unless they were uninstalled or removed and then reinstalled. This issue dates back as far as May 14.
Apple says that all user issues have been resolved so far. Apple confirmed that the issue arose in connection with a temporary fix for a bug in Apple's home sharing system.
Previously the bug was reported by a user of iOS 13.5 This app is no longer shared with you, requiring them to repurchase the app from the App Store before they can continue using it.
Apple's wave of fixes for this bug involved other users and programs that were not affected by the home sharing bug, so users will need to re-download almost all of the affected apps.
Fixing it when the next iOS and iPadOS version is updated is the most logical solution, but re-downloading the affected apps is not a bad way to go for now.
Other than that, Apple didn't reveal anything else about the cause of the problem or any other details.