Today this happened with me twice, I’m logged in www.codechef.com but when opening discuss.codechef.com a bar above appeared saying me to log in at www.codechef.com but when opening www.codechef.com shows that I’m already logged.
My account is not hacked. I’ve not logged out also. This problem is on your end.
Basically, the problem is discuss.codechef.com is not in sync with www.codechef.com . At an instant of time, discuss.codechef.com says me to log in at www.codechef.com while www.codechef.com shows my username in the top right side. I refreshed discuss.codechef.com 3-4 times so that I can write this here.
Upd - Attaching Screenshot.