The following article from Windows Central confirms rumors about why November 2019 Update isn’t a full Windows 10 build but rather a service pack. As you can see, Version 20H1 is about to RTM (release to manufacturing), sooner than Windows Insiders predicted:
To expand what the article says (and based on other sources I can gather):
A few years ago Windows development was put under Azure development. Because Microsoft Azure uses an outdated version of Windows Server platform, it needed to catch up with technologies introduced in newer Windows Server releases such as 2016 and 2019, which are both cloud optimized. In order to do that, Azure and Windows developers had to be on the same development schedule, and given the fact that Azure releases were done in June and December and Windows targeted March and September, something had to be sacrificed; and that sacrifice is Windows 10 November 2019 Update: rather than a full Windows 10 release, it is a service pack on top of May 2019 Update.
Based on the article linked, Windows 10 Version 20H1 is done – it is going through bug fix phase, typically done for several months prior to RTM and general availability a few weeks later. Although it is scheduled for December, it will still carry 20H1 codename because public release will be done in 2020. This means some of us (Windows Insiders) will be moved to 20H2 (codenamed “Manganese”, targeting June 2020) in a few weeks, which also explains why slow ring Insiders will be moving to 20H1 builds soon.
The things I noted above will have huge implications for this forum cluster, which I’ll outline in an upcoming “state of the list” post.