Microsoft rolling out March optional cumulative update for Windows 10 November 2019 Update (version 1909) and Windows 10 May 2019 Update with several fixes and improvements. This is an optional update and it won’t download or install automatically on your device unless you manually select ‘Download and install’ in Windows Update page. The key changes include fixes for an issue that prevents the mute button from working on certain devices with the Your Phone app and fix for a bug crashing File Explorer. You can open the Settings app and click on the Windows Update option to install the patches.
Source: https://www.bleepingcomputer.com/news/microsoft/windows-10-optional-cumulative-update-kb4541335-released/