Muting Lichess through browser tab volume button broken?

I noticed that if I mute Lichess through my browser tab volume button I'm still getting the "clop" of moves coming through every now and again. If you are watching LichessTV (and not logged in) and mute the site this way I think every time the game changes the first move is still heard?

Also noticed this. Firefox? I imagine this more a browser bug than a lichess bug.

Yes, probably a browser problem, I use Chrome and the mute option works just fine.