Thank you for reporting this issue.
You are not logged into someone else’s account. It’s your account only.
As we have mentioned earlier, the new CodeChef discuss is based on Discourse. Now, there is a small piece of code which does not allows users to have ‘_’ (underscores) as the last character in their usernames.
return unless errors.empty?
if username[-1] =~ /[^A-Za-z0-9]/
self.errors << I18n.t(:'user.username.must_end_with_alphanumeric')
So, ‘ryuk___’ became ‘ryuk’.
The user registered with ‘ryuk’ on CodeChef (https://www.codechef.com/users/ryuk) has never logged into discuss before.
If he tries to login in the future, he will be assigned ‘ryuk1’ as his username.
So, you are using your account only and not someone else’s account.
And, this is not how it should have been (the stripping of underscores from the end of usernames). We are working on finding a suitable fix for this issue.