Windows Server 2012 and 2012 R2 reaching end of support

Windows Server 2012 and Windows Server 2012 R2 will end onOctober 10, 2023. After this date, these products will no longer receive security updates, non-security updates, bug fixes, technical support, or online technical content updates. If you cannot upgrade to the next version, you will need to use Extended Security Updates (ESUs) for up to three years. ESUs are available for free in Azure or need to be purchased for on-premises deployments.

Windows Server 2012 was the first release of Windows Server to entirely remove the Windows classic UI, if I recall correctly and my quick research today didn't fail me. Meaning, if you want the latest version of Windows that still carries the classic user interface, you're going to have to go all the way back to Windows Server 2008.