Probably a faulty theme:
lookandfeeltool -a org.kde.breeze.desktop
#log out/in
If that doesn’t work:
cd /home/<your-username>/.config
mkdir plasma-old
mv *rc plasma-old/
mv kdeglobals plasma-old/
reboot
Probably a faulty theme:
lookandfeeltool -a org.kde.breeze.desktop
#log out/in
If that doesn’t work:
cd /home/<your-username>/.config
mkdir plasma-old
mv *rc plasma-old/
mv kdeglobals plasma-old/
reboot