Greasy Fork is available in English.
Clone of h264ify with optional limit up to 30 FPS.
The default code limits the framerates (fps) to 30, and the best YouTube offers for high framerates (50fps+) videos at 30fps are (nowadays) 720p.
If you want to change that:
-1. view the code;
-2. enable "Allow edits";
-3. search for: "const BLOCK_HIGH_FPS = true;";
-4. chage it to: "const BLOCK_HIGH_FPS = false;".
Maybe the developer can add a button on the Violentmonkey (or simillar) dropdown menu when in the site to toggle this parameter.
When I enable this script YouTube videos won't go above 720p resolution. Not sure if there's something I need to edit in the code to fix that.