Cannot apply Kvantum theme into any qt app from flatpak

[vuongtuha]

no matter qt5 or qt6, example below
flatpak run --env=QT_STYLE_OVERRIDE=kvantum --filesystem=xdg-config/Kvantum org.kde.haruna

(haruna:2): Gtk-WARNING **: 16:54:03.934: Theme parsing error: gtk.css:6754:15: Junk at end of value for padding
unknown() : QApplication: invalid style override 'kvantum' passed, ignoring it.
	Available styles: Breeze, Windows, Fusion

I really cannot guess anything could be reason

[vuongtuha]

dnf list --installed | grep kvantum

kvantum.x86_64                                       1.1.4-1.fc42                         updates
kvantum-data.noarch                                  1.1.4-1.fc42                         updates
kvantum-qt5.x86_64                                   1.1.4-1.fc42                         updates

native pkg app would worked fine. Idk any appimage to AB test myself

[tsujan]

Sorry, I can't help you because I don't use flatpak or things similar to it. Someone knowing flatpak might have an answer though.

Also, you might want to ask your question in flatpak forums.

[NickLion]

Flatpak runs applications in their own file system abstraction, so they don't see your system root FS along with system installed Kvantum. Bypassing this is not advised too, as Flatpak runs with its own set of libraries which can be incompatible with your system ones.
So you should install Kvantum inside of Flatpak root. Check this instruction if it'll work for you:
https://www.reddit.com/r/linux/comments/psit31/flatpak_now_supports_qt_theming_with_kvantum/