Yeah, not only did the old tab design have an indicator what tab was playing audio, it actually was more helpful since the audio indicator did not take over the favicon. I could clearly see that it was YouTube's favicon next to the speaker icon - now I only see the speaker icon.

I didn't mean the icon, but there's now a line for actual text besides the page title, which I'm assuming is/can be used to display useful info.

Can it? My bar is full of tabs so all I see there is "PLAY" (the fading at the end of the button makes the "I" and "N" hard to see and the "G" is completely gone)

I would assume so, but as said, I have vertical tabs so I'm not really using it myself. If it doesn't now then it at least seems obvious it can in the future.

True - my only gripe with it is that video icon is in the same place - if I have 5 YouTube tabs, 1 playing, that one with audio icon is very hard to distinguish from the other 4 with video icons. Not sure if video icon is useful to some people at all, especially since it's shown even if video is not actively playing.

Huh, for me the speaker icon doesn't show unless I mouseover the tab. So I can't see which tab is playing at all. And the Muted/un-muted icons are almost identical.