Application.UserIdentity in .net8 not available

Hey there,
i´m trying to use Application.UserIdentity but Visual Studio throw the  CS0117 “Applicaton” has no definiton for “UserIdentity”  Error.
Also the VS Information says its available to net48 but not to .net8.

Is there any Solution or Workaround for it?
Or it s really not more available in .net8?

Thanks
Luca