flatpak crashes

### System Information

debian forky

### LMMS Version(s)

1.2.2

### Most Recent Working Version

_No response_

### Bug Summary

flatpak (stable from flathub) won't start :
```
kro@thinkpoutre ~ flatpak run io.lmms.LMMS
Failed to create wl_display (No such file or directory)
qt.qpa.plugin: Could not load the Qt platform plugin "wayland" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: eglfs, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.
```

Reinstalling doesn't change anything.

I use wayland and pipewire with GNOME on debian forky. nothing special I can think of, sorry !

### Expected Behaviour

application running ?

### Steps To Reproduce

install flatpak stable from flathub and run it.

### Logs

_No response_

### Screenshots / Minimum Reproducible Project

_No response_

### Please search the issue tracker for existing bug reports before submitting your own.

- [x] I have searched all existing issues and confirmed that this is not a duplicate.

No files, tests, or code entry points are mentioned. First reproduce with `flatpak run io.lmms.LMMS` on Debian forky using the stable Flathub package, then investigate the reported Qt Wayland initialization failure. Done means the Flatpak launches successfully in the reported Wayland and PipeWire environment.

Written by the indexing model from the issue text.