Greasy Fork is available in English.
This script will revert all UI changes prior to late 2022 (which disables rounded corners on everything and reverts 2019-2022 backgrounds.)
< Feedback on YouTube - Revert UI changes before late-2022 (Non-Rounded Design)
the same
It doesn't always work, sometimes it's a normal interface, sometimes it's a new one from YouTube, you have to refresh the page
Works great, but sometimes I need to refresh the page for it to apply properly. (For example, when I open in a new tab, the UI changes wont be applied sometimes)