Just experienced the same, signed up to log this issue, but checked before posting and the site (auth) is back up. I also got asked to create a tenant when logging in, but this also is resolved (at least for now). Hope it’s back working for you now.
At this moment, it seems like no incident has been reported on our Auth0 Status page, but we will investigate and see what happened.
In the mean time, could you please try once more to access the Auth0 Login page and see if anything changed? @samellis462 reported the issue to have been resolved on their end, hopefully this is reflected for everyone, but please let us know.
Returning with a small update, a system outage incident took place which has affected some users, but we are receiving confirmations that of more environments becoming fully operational once more.
While we continue to investigate and monitor the situation, please let us know if you are still experiencing issues on your end, or if everything returned to normal.