www.youtube.com/##.paper-toast-open.yt-notification-action-renderer.style-scope.toast-button

I believe it was this one, just add it as part of the filter list in ublock

The extension I used for user agent was this one. I don't think it matters what you spoof as, but I chose to spoof as chrome. https://addons.mozilla.org/en-US/firefox/addon/user-agent-string-switcher/

So far it worked and I'm back to no ads and no interruptions