I'm with Windows 11, Studio 2021 behaved normally up until now.

Last night, a Windows 11 update was performed.

This morning, when I tried to open Studio 2021, I got the following message:

Unable to start service Sdl.TranslationStudio.Api.ProjectManagement.IProjectManagementService

I looked upon KB and performed the suggested turnaround.

Then I uninstalled Studio 2021 making sure to delete all reference to Studio 2021 (project template, Plug-ins...)

Installation proceeded smoothly and completed normally.

Upon starting Studio 2021, I get the same error message over and over.