SUMMARY When switching from dark to light theme, xdg-desktop-portal-kde emits SettingChanged with color-scheme set to 2 (prefer light). kde-gtk-config sets org.gnome.desktop.interface.color-scheme to 0 which makes xdg-desktop-portal-gtk to emit SettingChanged with color-scheme set to 0 (no preference). xdg-desktop-portal-gtk emits later thus applications use its value. STEPS TO REPRODUCE 1. Switch Plasma to a dark color scheme and back OBSERVED RESULT SettingChanged is first emitted with 2, then 0 EXPECTED RESULT SettingChanged is emitted both times with 2 SOFTWARE/OS VERSIONS Operating System: NixOS 25.11 KDE Plasma Version: 6.4.5 KDE Frameworks Version: 6.18.0 Qt Version: 6.9.2 Kernel Version: 6.17.0-cachyos (64-bit) Graphics Platform: Wayland Processors: 32 × AMD Ryzen 9 5950X 16-Core Processor Memory: 64 ГиБ of RAM (62.7 ГиБ usable) Graphics Processor: AMD Radeon RX 6400 Manufacturer: Micro-Star International Co., Ltd. Product Name: MS-7C94 System Version: 1.0 ADDITIONAL INFORMATION I believe xdg-desktop-portal is at fault too due to not checking which impl is responsible for the setting before forwarding the signal and I made a bug report for it too (https://github.com/flatpak/xdg-desktop-portal/issues/1842) but I don't know how fast they will fix it or will they fix it at all thus I believe it would be a good idea to synchronize the values.
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kde-gtk-config/-/merge_requests/137
Git commit 3ffc9bff69efd8cac6bacef2caac5903ca287855 by Ilya Fedin. Committed on 31/10/2025 at 19:47. Pushed by nicolasfella into branch 'master'. Use prefer light in light mode Changing org.gnome.desktop.interface.color-scheme leads to xdg-desktop-portal-gtk issuing SettingChanged for org.freedesktop.appearance.colo-scheme, which in turn gets forwarded by xdg-desktop-portal and applications use no preference mode instead of the prefer light mode suggested by xdg-desktop-portal-kde. Doing the same as xdg-desktop-portal-kde avoids the issue. M +1 -1 kded/gtkconfig.cpp https://invent.kde.org/plasma/kde-gtk-config/-/commit/3ffc9bff69efd8cac6bacef2caac5903ca287855
Git commit b4fdff4d365035460a0f915cf7a458708a1305b3 by Nicolas Fella, on behalf of Ilya Fedin. Committed on 31/10/2025 at 21:19. Pushed by nicolasfella into branch 'Plasma/6.5'. Use prefer light in light mode Changing org.gnome.desktop.interface.color-scheme leads to xdg-desktop-portal-gtk issuing SettingChanged for org.freedesktop.appearance.colo-scheme, which in turn gets forwarded by xdg-desktop-portal and applications use no preference mode instead of the prefer light mode suggested by xdg-desktop-portal-kde. Doing the same as xdg-desktop-portal-kde avoids the issue. (cherry picked from commit 3ffc9bff69efd8cac6bacef2caac5903ca287855) M +1 -1 kded/gtkconfig.cpp https://invent.kde.org/plasma/kde-gtk-config/-/commit/b4fdff4d365035460a0f915cf7a458708a1305b3