It can be as simple as redirecting the old tab to some other fake site by setting window.opener.location.href. If the redirected site looks close enough to original site and asks user to login again, the unsuspecting user thinks that he got logged out and may enter login credentials.
Oh... May be you meant an actual website which is making use of this attack 😂. If so, i don't know of any such site, we have to wait for someone else to answer it.