Your handle only works on the instance you signed up on (lemmy.one).You can view communities from all other federated instances (lemmy.ml,etc) from your home instance (again, lemmy.one). You shouldn’t be trying to sign into other instances with your handle
I’m reading in some other threads that it may be due to the cloudflare DDoS protection in place.
There are a bunch of comments in this thread on kbin.social at https://kbin.social/m/[email protected]/t/26213/XKCD-1172 but none here at lemmy.one. Every time I think I understand federation I get thrown for a loop