We are moving into the final stages of cleaning up our new authentication method: Sign in with Forem. This new authentication option allows your members to use the same login across Forems. Way more information coming soon as we move out of the limited beta.
This feature was previously called "Passport". One of the things we are cleaning up right now is that naming. So if you opted in to try Passport on a self-hosted Forem, we need you to upgrade your Forem instance. Right now, because of the renaming, if you try to login with "Passport" you will get a missing Client ID error. Anyone with Cloud hosting has already been upgraded.
If you haven't discovered this authentication method or turned it on for your Forem, you don't need to do anything. But it's probably wise to upgrade your Forem anyway. Always a good bit of site hygenine to do regularly and then you will get to use the see the new member detail view as well as tons of other features.