the current ones look nearly identical and are hard to distinguish. please consider something different here. e.g. a full speaker (on) versus an outline speaker (off) icon.
These new icons: - Look bad. The outline is too thin, leaving it looking "pixelated" and crusty, as anti-aliasing doesn't have enough meat to work with - terrible for anybody with less than perfect vision. I'm the recommended arms length away from my monitors and I have a legitimately hard time distinguishing muted and unmuted. Somebody with astigmatism, diabetes, you name it probably won't be able to tell the difference at all.
Also the "start playback"* button in tab (when automatic playback is disabled) before was easily distinguishable from mute/unmute, as it had circle around it, while the mute buttons didn't. Now, when everything has a circular outline it's harder to spot at a glance which of many YT pages is playing, and which ones can still be started without switching to the tab. I sometimes open several videos with middle-click, so one is playing, with speaker icon, rest are to be played with the other icon. Now it's hard to see which are which, as everything has a circle with something in it as the icon.