The login gating on Twitter was relatively recent (within a year or two, IIRC) before Musk took over, and also relatively mild. Non-logged-in users could still read most tweets, conversations, lists, etc. It was annoying and user-hostile though.

When Musk's people took over they very briefly removed any login gate, then very soon after they completely blocked all meaningful non-logged-in access to the site. Which is frankly fine with me: it's a good reason to never visit a place that has become a cesspool of scams, porn, and white supremacist propaganda.