For Windows Insiders in slow and release preview rings: KB4556803 (build 19041.264) is no its way:
• We have fixed a performance issue in Windows Mixed Reality (WMR) that prevents it from working correctly for many users.
• We fixed an issue that prevents cleaning tools, such as Disk Cleanup, from removing previously installed updates.
• We have updated the 2020 start date for daylight saving time (DST) in the Kingdom of Morocco. For more information, see KB4557900.
• Security updates to Internet Explorer, the Microsoft Scripting Engine, Windows App Platform and Frameworks, Microsoft Graphics Component, Windows Input and Composition, Windows Media, Windows Shell, Microsoft Xbox, Microsoft Edge, Windows Fundamentals, Windows Cryptography, Windows Authentication, Windows Kernel, Windows Virtualization, Windows Update Stack, Windows Core Networking, Internet Information Services, Windows Network Security and Containers, Windows Active Directory, Windows Server, and the Microsoft JET Database Engine.
Note: until it is publicly released to everyone, Version 2004 (May 2020 Update) cumulative update announcements should serve as milestones, not servicing releases (although being serviced like a typical release, it is only available for Insiders).