pavucontrol has buttons for mute, link channels and set fallback. These buttons have icons but they are missing if x11-themes/gnome-icon-theme is not installed. I had this on lxqt and kde (aka non-gnome) systems. Please add the dependency to gnome-icon-theme (unless some patch exists to use other icons, e.g. icons from kde) Reproducible: Always
I don't know when it was added, but the dep on virtual/freedesktop-icon-theme is in both versions.