Microsoft officially confirmed that all editions of Windows 10 21H1 are set to reach their end of service at the end of November, and after that the devices running this version will no longer receive monthly security and quality updates containing protection from the latest security threats.
Microsoft recommends that any users still using Windows 10 21H1 on their devices should upgrade to the latest version of Windows 10.
Microsoft announced the availability of Windows 10 22H2 back on October 18th, and is now rolling out to all eligible devices.