@sunsey Thank you for sharing this example. This is precisely why the button is problematic for me too. I tend to have a music app in a pinned tab like yourself, but the mute button being present means that there is a very small margin that I can click to switch to the tab without accidentally muting my music. The #enable-tab-audio-muting flag does exist, and I have set to Disabled, however the flag appears to have no effect.

Opera One (version: 101.0.4843.43)
Update stream: Stable
System: Windows 10 64-bit
Chromium version: 115.0.5790.171