This Windows 10 Health Report provides an overview of the problems people encounter with the recently released Windows 10 2004 KB4566782 and 1909 KB4565351 cumulative updates. Problems could include issues installing the update, visual bugs, or problems printing due to a new security fix. The most common error being shown when installing the updates is 0x800f081f, which is commonly caused when the Windows Update cannot find the files it is trying to install. The biggest problem you are likely to run into is getting the update installed in the first place.
Source: https://www.bleepingcomputer.com/news/microsoft/windows-10-updates-health-report-kb4566782-and-kb4565351/