[alsa] GitHub skyline plays audio at tab load despite being muted

Somehow the GitHub skyline commit history visualizer site can play audio when the tab loads even though it's muted. For example this one from the downstream report https://skyline.github.com/pacien/2021

We've only been able to reproduce it on Linux using Pipewire and ALSA, everything works as expected with Pulse. Also I couldn't find any other reproducers. I don't know what they are doing differently.

Downstream report here: https://github.com/qutebrowser/qutebrowser/issues/7179
They are on Nix but I can reproduce on Debian.

Here's some example C++

#include <QUrl>
#include <QApplication>
#include <QWebEngineView>
#include <QWebEngineSettings>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QWebEngineView view;
    view.page()->setAudioMuted(true);
    view.page()->settings()->setAttribute(QWebEngineSettings::PlaybackRequiresUserGesture, false);

    view.load(QUrl("https://skyline.github.com/pacien/2021"));
    view.show();

    return app.exec();
}