I just checked too. And if you close popup it takes you do another login page (also with an X) but that one can't be closed. So apparently there is no way to browse Twitter without an account now, which you could before.

People always used to claim that getting banned from twitter meant you were cut off from important information. It's highly debatable that there was any important information on twitter. That aside it wasn't really true you were cut off entirely, you could still browse tweets, just couldn't post when banned. Now it seems being banned does mean you're cut off from reading it.