Thanks for the report jvz. Since GitSCMFileSystem.build() was implemented by stephenconnolly in 2016, I assume that the credentials API support for user-scoped credentials, authorize project scoped credentials, other credentials, and the credential shadowing feature were added to the credentials API after 2016. Can you confirm my assumption?
If my assumption is correct, then I assume all uses of credentials in the git plugin and the git client plugin should probably be visited to assure they are using the correct and current credential APIs.
If those features were not added to the credentials API after 2016, then I assume there was a compelling reason that they were not used in that implementation.
I'm also open to updating the credentials plugin API if there's a limitation here I missed back when I first updated that.