System.ServiceModel.Primitives does not seem to be compatible with .net 6

[JonSaffron]

Although NuGet says that the package is compatible with .net 6, and there is no problem bringing in the package, I cannot get Visual Studio to see anything in the System.ServiceModel namespace with the exception of the Syndication namespace.

To Reproduce
Create a test project targeting framework net6.0.
Add package System.ServiceModel.Primitives 8.1.0
Note that none of the expected objects in the System.ServiceModel are available
Change the targeted framework to net8.0
Note that the expected objects now become available

Expected behavior
Either for nuget.org to clearly show that the package is NOT compatible with .net 6 (as it was with version 8.0.0),
OR for the package to be made compatible with .net 6