Today’s daily ISO for Bionic Beaver 18.04 sees an experimental switch to the Breeze-Dark Plasma theme by default.
Users running 18.04 development version who have not deliberately opted to use Breeze/Breeze-Light in their systemsettings will also see the change after upgrading packages.
Users can easily revert back to the Breeze/Breeze-Light Plasma themes by changing this in systemsettings.
Feedback on this change will be very welcome:
You can reach us on the Kubuntu IRC channel or Telegram group, on our user mailing list, or post feedback on the (unofficial) Kubuntu web forums
Thank you to Michael Tunnell from TuxDigital.com for kindly suggesting this change.