I remember hearing something like "the way Nitter worked, guest accounts, was shut down and the 3 instances that remain work by using selfbotting" a while ago, it's logical although I haven't verified it
I’m not sure how Twitter ultimately blocked them. It would be pretty embarassing (for Twitter) if it were a simple IP block of the Nitter.net servers, but that doesn’t seem too out of whack with Musk’s history of litigating bot behavior…