Microsoft rolled out the Windows 10 KB5009543 cumulative update through Windows Update, WSUS, and the Microsoft Update Catalog. It contains numerous bug fixes and performance enhancements.
Microsoft rolled out the Windows 10 KB5009543 cumulative update on January 11 for Windows 10 21H2, 21H1, and 20H2, upgrading the system version numbers to Build 19042.1466, 19043.1466, and 19044.1466, respectively. If you are using the Consumer Edition, this update does not apply to the May 2020 Update (version 2004), but the same update will be available on devices using the Enterprise or Education SKUs.
The update is available through Windows Update, WSUS, and the Microsoft Update Catalog. It contains numerous bug fixes and performance enhancements.
Full list of updates:
Windows 10 version 1507 - KB5009585 (OS internal version 10240.19177)
Windows 10 version 1607 - KB5009546 (OS internal version 14393.4886)
Windows 10 version 1703 - EOS
Windows 10 version 1709 - EOS
Windows 10 version 1803 - EOS
Windows 10 version 1809 - KB5009557 (OS internal version 17763.2452)
Windows 10 version 1903 - EOS
Windows 10 version 1909 - KB5009545 (OS internal version 18363.2037)
Windows 10 versions 2004, 20H2 and 21H1 - KB5009543 (OS internal versions 19042.1466, 19043.1466 and 19044.1466)
As with each Tuesday patch, you can check for and install new updates by going to Settings, clicking Windows Update, and selecting Check for Updates to install updates.
Windows 10 KB5009543 changelog: