This add-on works great, but why is there not a set-able shortcut? It badly needs that.

機能は問題ありません。が、タブバー上の全てのタブにミュートアイコンが表示されて消すことができず、Firefox91に更新してから、このミュートアイコンがあるせいで webサイトのファビコンが表示されず、どのタブが何のサイトなのか視認できず、使いづらい。なので、このアドオンは削除して、音量ミキサーでFirefoxをミュートにして、必要な時だけこれを解除して音を出すことにしました。このアドオンを無効にすることで、webサイトのファビコンは正常に表示されますが、タブをミュートにすると同様にファビコンが消えてしまうので、Firefox側でこの問題が修正されるのを待つよりありません。

Basically good, but for me it doesn't mute tabs with flash content

UPDATE: 11/24. I have noticed recently that the tab automatically mutes several times during youtube videos. Occasionally, it won't allow me to listen at all. Uninstalled, until it I can trust again.

I love that all my tabs are automatically muted, as I often click on several videos at once!
What's REALLY annoying, is when websites have embedded audio/video that starts immediately making noises and I can't even tell where it's coming from!
So, thanks for this! LOVE IT!!
I have not figured out how to remove the notifying icon from my tabs. Is that even an option, at this point?
This is useful, for sure, to see the status of each tab, but maybe an option to "whitelist" certain sites/pages to always or never show up.
Since there are no vids on the addons pages, for instance, I don't need to see the icon (nor even have the need of the feature), but it takes up space and blocks the tab titles for quick reference.
Thanks so much for this, dev!