From Reminder: End of servicing for Windows 10, version 21H1 (https://techcommunity.microsoft.com/t5/windows-it-pro-blog/reminder-end-of-servicing-for-windows-10-version-21h1/ba-p/3671327):
QuoteStaying protected and productive
To help keep devices protected and productive, Windows Update will automatically initiate a feature update for devices running Home and Pro (non-domain joined) editions of Windows 10, version 21H1 that are reaching end of servicing. This keeps devices supported and receiving monthly updates that are critical to security and ecosystem health. Remember that you and your users can choose a convenient time (https://support.microsoft.com/windows/get-updates-when-you-re-away-from-your-pc-with-active-hours-in-windows-09b5376c-7647-4361-1423-c29aa692a8c4) for devices to restart and complete the update while remaining productive.
We will automatically update devices nearing end of servicing to the latest version of Windows 10 (https://aka.ms/W10/how-to-get-22H2), but you can opt to upgrade eligible devices to Windows 11 (https://blogs.windows.com/windowsexperience/2022/09/20/how-to-get-the-windows-11-2022-update/).
See the linked article for additional information.