https://www.bleepingcomputer.com/news/microsoft/windows-10-cumulative-update-kb4540673-and-kb4538461-released/

It's March 2020 and today is Patch Tuesday and Microsoft is rolling out a new cumulative update for all supported version of Windows. The cumulative update with security fixes is rolling out to PCs with November 2019 Update, May 2019 Update and October 2018 Update.

In March 2020 cumulative update for Windows 10 version 1909, 1903, and version 1809, there are only security enhancements for the system, browsers, core components and other basic functions.