This probably effects almost no one, but since its effects are so serious, I thought it worth a post just in case.
First, it only effects the win10 2004 or 20H1 build available to Insiders -- if this is the RTM for the spring 2020 version update [as alleged], I have no idea if it effects what's been given to OEMs.
Second, it only happens if you perform disk cleanup using the command prompt -- "dism /online /Cleanup-Image /StartComponentCleanup".
The result is that Windows will no longer start.