This update was released yesterday, May 19, 2022. It is applicable for Windows 10 versions 21H2, 21H1, and 20H2, as such, it is not available through Windows Updates and must be manually downloaded from the Microsoft Update Catalog website. If you are on one of these versions of Windows 10, and have KB5011831 optional preview cumulative update installed, having issues with MS store apps not functioning correctly install KB5015020 as a solution. More information is here at the Bleeping Computer website.
https://www.bleepingcomputer.com/news/microsoft/emergency-windows-10-updates-fix-microsoft-store-app-issues/
SA