Brightness can be set under systemsettings -> power management. Unfortunately, contrast cannot. There have been workarounds with colorschemes eg: https://www.reddit.com/r/kde/comments/nqkka3/guide_increasing_contrast_on_blurred_screens/
This is not something we ( kubuntu ) can fix. I would suggest doing a feature request upstream bugs.kde.org under systemsettings. Thanks ** Changed in: kwin (Ubuntu) Status: New => Opinion -- You received this bug notification because you are a member of Kubuntu Bugs, which is subscribed to kwin in Ubuntu. https://bugs.launchpad.net/bugs/1993027 Title: Display settings lost when leaving screen saver / screen switch To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/kwin/+bug/1993027/+subscriptions -- kubuntu-bugs mailing list kubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs