The script deletes all content on the homepage (recommendations and subscriptions), the related videos & autoplay/up next section on the watch page, the videowall of recommendations that shows up when a video is finished playing, and the intrusive shelves that show up in search results (e.g. "Shorts", "For you", "Previously watched", "People recently watched", etc.).

For your convenience it also auto-focuses the search bar on the home page when it loads.

There are configuration variables at the top of the code that allow you to keep specific features available, or add additional HTML selectors to delete. You can also disable the search bar auto-focus if you don't like it.