SUMMARY

In Plasma 6, when a Global Theme is applied, specific overrides (such as ColorScheme or WidgetStyle) are frequently stored in ~/.config/kdedefaults/kdeglobals rather than the base ~/.config/kdeglobals.

When using the "Apply Plasma Settings" button in the Login Screen (SDDM) settings module, the utility only syncs the base kdeglobals file to /var/lib/sddm/.config/. Because it ignores the kdedefaults overlay, the SDDM greeter falls back to system defaults (e.g., Breeze) instead of the user's actual active theme.

STEPS TO REPRODUCE
1. Apply a Global Theme that utilizes kdedefaults for its color scheme (e.g., Utterly-Nord).
2. Verify that ~/.config/kdeglobals contains ColorScheme=Breeze while ~/.config/kdedefaults/kdeglobals contains the actual active scheme (e.g. ColorScheme=UtterlyNord)
3. Go to System Settings > Login Screen (SDDM) and click "Apply Plasma Settings"
4. Logout or check /var/lib/sddm/.config/kdeglobals

OBSERVED RESULT

The synced kdeglobals in the SDDM directory contains the "base" Breeze setting. The greeter appears with incorrect colors/styles.

EXPECTED RESULT

The Sync utility should perform a KConfig merge of the user's active configuration (including the kdedefaults layer) before writing the result to the SDDM configuration directory.

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: Kubuntu 25.10
KDE Plasma Version: 6.4.5
KDE Frameworks Version: 6.17.0
Qt Version: 6.9.2

ADDITIONAL INFORMATION

Workaround: Manually merging the contents of ~/.config/kdedefaults/kdeglobals into /var/lib/sddm/.config/ kdeglobals resolves the issue.