I've just completed an Arduino-based project.
I was hoping to share it on the Arduino website, but the Project Hub page is supper buggy.
It won't let me sign-in, and when I stay on the page long enough, or when I attempt to sign-in I get an:
"503 first byte timeout" error.
I got that same error in Internet Explorer and Google Chrome web browsers.
Hmm working just fine here.
Are you logging into the main Arduino site first as this site uses an SSO (single sign on) to get to project hub.
Passwords are also case sensitive.
We have been experiencing outings with the Hackster.io servers that have been resolved yesterday. It was not affecting all servers, that's why you were experiencing the 503 just at times.
Thanks for your report!