In Dynamics Portals, we can use auth0 as an identity provider. This works. However, the portal logout does not logout of auth0 which means that after a user has "logged out" their auth0 token is still valid. When the user next clicks sign-in on the portal they are logged in immediately without having to re-enter their username and password. Logout should mean that the user has to re-authenticate when next visiting the portal site.
There is a workaround which is not elegant and it would be great for the portal to support logging out of auth0.