I was able to resolve this for a user without deleting the user.
I had this issue on a Lenovo.
wsappx was causing high CPU, fully occupying a single core. Upon logon the user had a black screen post KB4093112 update and to make matters worse the start menu and some other buttons were no longer working if the black screen finally dissapeared.
I had two user accounts on the laptop. A local account that was not affected and a domain account that got affected by this issue.
I did the following operations on the local account that was not affected. If you only have one account. Use task manager and start cmd as administrator to make a new user account to do these operations.
With the non impacted account, launch powershell as administrator and run:
Get-AppxPackage -User <impactedusername> | Remove-AppxPackage
This will spawn some errors but keeps processing. Once done open explorer and navigate to c:\users<impactedusername>\appdata\local\
Rename the directory "Packages" to Packages.backup
Now reboot the computer and login as the impacted user. Windows will recreate basic AppxPackages that we removed and create a fresh start menu. wsappx will no longer be crashing and will be updating packages properly now. If needed, you can reinstall build in apps
https://www.cnet.com/how-to/how-to-reinstall-default-apps-in-windows-10/