Cloudflare powers a lot of internet infrastructure, one small part of which is the login / authentication systems for FanGraphs and Ottoneu. We’re monitoring this issue and will update when it is resolved.
Pretty widespread!
This is directly the service having an issue that is preventing FG/Ottoneu auth. They seem to be on a path towards resolving this issue just over one hour into it.
I was just able to log in to Ottoneu via FanGraphs