I didn't need to log in: I got the rest of the thread by following the link "see rest of this thread". That link though is easy to miss, what with being somewhere mid-page and being surrounded by elements that are visually much louder, and I, too, wish that no one here would submit or upvote links to Twitter.
Twitter seems to be doing some kind of A/B testing. Clicking the "See rest of this thread", pops up a login window, which on being closed takes you back to the initial page.
I had this issue, sussed it in about 10 min. If you're in a Chrome-based browser (incl Brave), DL the Ublock Origin extension, then: Extension options > "My Filters" > add one of the filters in the reddit thread linked.
(https://www.reddit.com/r/uBlockOrigin/comments/p5lgcv/twitte...)