I found an old ticket https://pagure.io/fedora-infrastructure/issue/10516 which is what I used to see in the past - that I got 500 server error and when I refreshed I was able to log in.
But not today - today I can't log in by any means - refreshing doesn't help, nor do private browsing window or another browser.
There was an issue with the saml2 data on our end.
It's been fixed.
Please retry and if you still see it, reopen this...
Metadata Update from @kevin: - Issue close_status updated to: Fixed - Issue status updated to: Closed (was: Open)
Fixed, thank you!