the Telegram flatpak does not start, if within a GNOME Wayland session.

Trying to start it manually, this is the output:

flatpak run org.telegram.desktop 

(process:2): Telegram-WARNING **: 16:39:07.608: Unfortunately, GTK integration
conflicts with qgtk2 platformtheme and style. Therefore, QT_QPA_PLATFORMTHEME
and QT_STYLE_OVERRIDE will be unset.
Telegram-Message: 16:39:07.609: This can be ignored by setting
TDESKTOP_I_KNOW_ABOUT_GTK_INCOMPATIBILITY environment variable to any value,
however, if qgtk2 theme or style is used, this will lead to a crash.
Telegram-Message: 16:39:07.609: GTK integration can be disabled by setting
TDESKTOP_DISABLE_GTK_INTEGRATION to any value. Keep in mind that this will lead
to clipboard issues and tdesktop will be unable to get settings from GTK (such
as decoration layout, dark mode & more).
qt.qpa.xcb: could not connect to display 
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" 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.


Trying to run it like this:

QT_QPA_PLATFORM=wayland-egl flatpak run org.telegram.desktop

it does start.

On an Xorg session, it starts without issues.

I'm reporting this here instead than to Telegram or flathub directly, is that
installing exactly the same flatpak on, e.g., Fedora or Ubuntu works flawlessly
while inside a Wayland session. So it feels like it's something specific to
openSUSE.