This is a surprising change. It works even without JS, although as others have mentioned, without all the content.
6 years ago, pre-Musk, they started forcing the JS-only webapp and everyone absolutely hated it: https://www.bleepingcomputer.com/news/technology/twitter-war...
I wonder if there's a group of developers at X, especially with Musk's cost-saving direction, who are slowly bringing back the static pages.