https://wccftech.com/windows-10-2004-end-of-service-on-december-14/

Microsoft has released a reminder for those still running Windows 10 May 2020 Update (version 2004) on their devices. The operating system will meet its end of service deadline on December 14, 2021, which means you will no longer receive security or quality updates on your devices running version 2004. The company writes:

On December 14, 2021, all editions of Windows 10, version 2004 (20H1) will reach end of service. After that date, devices running these editions will no longer receive monthly security and quality updates.