Windows 10 version 2004 feature update, which was released to consumers and enterprises last month, may lack update deferral options in the Settings. Microsoft says this change is intentional as the company is simplifying Windows Update experience on Windows 10.
Windows 10’s Advanced Update options allowed users and administrators to defer feature updates to block Windows 10 feature updates installation on devices that they manage.
Last year, we changed update installation policies for Windows 10 to only target devices running a feature update version that is nearing end of service. As a result, many devices are only updating once a year. To enable all devices to make the most of this policy change, and to prevent confusion, we have removed deferrals from the Windows Update settings Advanced Options page starting on Windows 10, version 2004. If you wish to continue leveraging deferrals, you can use local Group Policy (Computer Configuration > Administrative Templates > Windows Components > Windows Update > Windows Update for Business > Select when Preview builds and Feature Updates are received or Select when Quality Updates are received).