I hadn't noticed. Why has it gone, do you know?
officially the developer mentioned that the changes the youtube devs broke it completely in firefox and slightly broke it in chrome so he stopped it temporarily.
I hope @MaximeRF find the time/motivation to fix it. I just was reminded it'd gone when I went to use the boost volume feature.
I hope ad-blocking isn't the blocker, because uBlock Origin handles that (although I suppose uBO doesn't cover things like channel whitelisting).
but you can also get youtube channel whitelist for ublock origin to do that! https://addons.mozilla.org/en-US/firefox/addon/youtube-channel-whitelist/
I thought you were talking about the volume boost thing at first and was really surprised.
FYI: I keep using it, it kind-of-works for me if I open the tab in the background and let it load (< 1min) before focusing on it. It also works if I'm not logged in (e.g.: in incognito mode).
Better look at Freetube:
https://addons.mozilla.org/de/firefox/addon/freetube-redirect/
i have libredirect for somethings but i like youtube because i have certain creators i like and i like commenting and participating with them.
would recommend https://addons.mozilla.org/en-US/firefox/addon/youtube-addon/, idk if 100% of the features you mentioned are on there but worth a try
Firefox
A place to discuss the news and latest developments on the open-source browser Firefox