If you open someone's name in a new tab you sometimes can not add them as someone to follow if they are registered in a different domain name than you

But if you search for their name while in the domain you are registered you seem to be able to add them as someone to follow even if they are registered for a different domain, as long as the window you are using is currently at your own domain and not their domain.

Or maybe if you do not open their name in a new tab but click on it

Sometimes