https://wccftech.com/microsoft-releases-windows-10-update-kb5005103-for-v1909/

Microsoft has released "preview" updates for Windows 10 versions 1909 and 1809. Known as the C release updates, these updates bring the improvements and fixes that eventually become part of the mandatory Patch Tuesday updates of the next month. Since these are optional preview updates, we don't recommend getting these unless you are an experienced user and can deal with any surprises.

Windows 10 KB5005103 (Build 18363.1766) is available for version 1909 and KB5005102 (Build 17763.2145) is available for Windows 10 version 1809. Here are the highlights of these updates: