Plasma system "mute" button doesnt work

Grayjay Version: [7](https://github.com/flathub/app.grayjay.Grayjay/pull/7#issuecomment-2920632596)
OS: Manjaro(Arch based)
Desktop:
KDE-Plasma: 6.3.5
KDE-Frameworks: 6.14.0
QT-Version: 6.9.0

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Using the applications "Mute" button on KDE Plasma doesn't work for the Flatpak, for the native version it works.
Setup:
Have Grayjay installed and started, a video (with sound) playing.

#### **Expected behavior**(as with the native Grayjay version):
1. Click the "mute" button in the Plasma Panel(taskbar)
2. Now the Grayjay audio stream also gets disabled in the Plasma audio manager:
3. And obviously any video sound made by Grayjay gets muted.

### **Actual behavior(Flatpak version):**
1.a) There is no "mute" button:

1.b) While Grayjay is open, have another audio stream running(in my case Firefox, but having the native Grayjay application or probably most other applications with a running audio stream also works)
1.1. The "mute" button appears
1.2. Click the "mute" button in the Plasma Panel(taskbar)
2. Now the *Firefox* audio stream also gets disabled in the Plasma audio manager:
_NOT_ the Grayjay audio stream, named "Chromium".

If instead of the Plasma Panel "mute" button, I use the audio manager(below "Lautstärke" in the screenshot) and disable the "Chromium" stream with the Grayjay logo next to it, it works as expected, however toggling the Grayjay logo "Chromium" stream _does not_ toggle the Plasma Panel icon's "mute" button.