Hover a thumbnail on youtube.com and click an icon at the right: "Not interested" and "Don't recommend channel"
< Feedback on YT: not interested in one click
OK, this is oddly inconsistent: It randomly chooses to NOT work, but at other times it works.
Works for me. I guess Youtube is serving you a changed site as they do to randomly selected users. See if you can find a specific sequence so that I can debug the problem myself.
It's odd that it doesn't happen all the time, it happens sometimes which... Is concerning.
It just broke again