https://www.bleepingcomputer.com/news/microsoft/windows-10-kb5005611-update-fixes-microsoft-outlook-issues/

Microsoft has released the optional KB5005611 Preview cumulative update for Windows 10 2004, Windows 10 20H2, and Windows 10 21H1. This update fixes bugs in Microsoft Outlook and makes it easier to mitigate the PrintNightmare vulnerability.

This cumulative update is part of Microsoft's September 2021 monthly "C" update, allowing Windows users to test the upcoming fixes before they are automatically deployed in the forthcoming October 2021 Patch Tuesday.