ViewTube & YouTube
sebaro
2020-08-21/13:29
Starting with version 2020.08.20, ViewTube supports YouTube's default layout only, for both desktop (www.youtube.com) and mobile (m.youtube.com) versions.

For the old layout (the user-agent workaround) use this version of the script:
http://sebaro.pro/viewtube/files/viewtube-old-youtube.user.js