YTBlocker by Omanjuu3

Blocks unwanted YouTube recommendations based on rules you set.

★ Features

Hides unwanted recommended video cards on YouTube (including those loaded via infinite scroll) by matching against the video title and/or channel name
Optionally hide all Shorts in bulk (Shorts blocking is all-or-nothing, no fine-grained rules)

★ Two ways to block

Quick block via the ⋮ menu. Right next to any video, block by its exact title or channel name in one click.
Keyword blocking from Settings. Register your own NG (block) keywords. Match against title, channel name, or both. Regular expressions are supported for more flexible rules.

★ Sync across devices
Settings are stored using Firefox's account storage, so your rules carry over to other devices signed into the same account. Local-only storage is also available if you prefer.

note:Sync depends on Firefox's own sync timing, and also requires "Add-ons" to be checked in your Firefox Sync settings. If the sync interval hasn't triggered yet, or add-on sync isn't enabled, your rules may not carry over right away.