OldWiki v1.1
I dislike the new Wikipedia UI on desktop and disagree with their claim that it makes it more user-friendly. I don't like the trend of constantly narrowing down your most important content just to appease mobile users. As such, this extension forces Wikipedia on desktop to render the old UI.
Please feel free to review and improve the code at https://github.com/weirdindiankid/oldwiki
This image uses a licensed icon from https://www.flaticon.com/free-icons/wikipedia
The code is licensed under the MIT license.