https://www.bleepingcomputer.com/news/microsoft/microsoft-windows-10-21h2-has-reached-end-of-servicing/

Multiple editions of Windows 10 21H2 have reached their end of service (EOS) in this month's Patch Tuesday, as Microsoft reminded customers today.

Since Windows 10 21H2 (also known as the Windows 10 November 2021 Update) will no longer receive security updates, customers are advised to upgrade to the latest release as soon as possible to avoid exposing their systems to attacks exploiting unpatched security vulnerabilities.