MSAL sign out does not appear to clear cache

I'm exploring the Active Directory B2C Xamarin Native sample from the Azure team.  It uses MSAL, the new Microsoft Authentication Library.  The sample's README says to use this to sign out:

App.PCApplication.UserTokenCache.Clear(App.PCApplication.ClientId);

That code is executed in TasksPage.xaml.cs.

I ran the sample, signed in, and then signed out.  I then clicked the sign in button again, and the app found my user in the cache.  I was signed in without entering my credentials again.

After signing out, I would expect the app to clear its cache and require users to provide credentials when signing in again.  This doesn't appear to happen, unless I restart the app.

Is this behavior by design?