Quiet Tube от Jorogumo4

Quiet Tube takes things out of YouTube. It does not replace your recommendations, hide your feed, or lock you out — it removes the parts of the interface you never asked for and leaves the video grid alone.

What it removes, all optional:

• Shorts — in search results, in video lists, and from the sidebar
• Horizontal shelves — For you, Breaking news, Playables, and the rest of the carousels with a "See all" button
• The related videos rail on the watch page
• End cards and the suggestion grid that appears when you pause
• Comments and live chat
• Ambient lighting, the glow behind the player that costs real GPU time
• Merch, ticket and product shelves
• Thumbnails that start playing when your cursor passes over them
• Promoted feed items and Premium upsells
• Sidebar clutter — Explore, Playables, "More from YouTube", footer links

What it adds:

• Control over how many videos appear per row
• A tighter spacing option
• Autoplay that stays off

The shelf setting works differently to other extensions. Rather than shipping a fixed list of shelves to hide, Quiet Tube reads the shelves that actually appear on your home page and lists them by name in the settings. New shelf types YouTube introduces later show up automatically, and it works in any language.

Privacy: no data is collected, stored, or transmitted. One permission (storage, for your settings), runs only on youtube.com, makes no network requests. No analytics, no third-party code.

Note: this does not block ads inside videos. Pair it with uBlock Origin, which handles that far better than a layout extension could.