idk if this helps, but it's called org.kde.plasma.volume and here is the source code https://invent.kde.org/plasma/plasma-pa/-/tree/master/applet
it's part of the plasma-pa package, so maybe try reinstalling that
idk if this helps, but it's called org.kde.plasma.volume and here is the source code https://invent.kde.org/plasma/plasma-pa/-/tree/master/applet
it's part of the plasma-pa package, so maybe try reinstalling that