It seems that Wikipedia is testing their new design. This new design only applied for few languages. Few that I know so far are Bahasa Indonesia, Japanese, and Portuguese.

Japanese page snapshot before redesign[1] and after redesign [2].

[1]: https://web.archive.org/web/20220629082528/https://ja.wikipe... [2]: https://ja.wikipedia.org/wiki/ウィキペディア