Thanks! While the issue described in this topic is not resolved, I have found that turning DDC/CI off (POWERDEVIL_NO_DDCUTIL=1) resolves the issue with the energy profile slider blinking (https://discuss.kde.org/t/energy-onsumption-profie-slider-in-taskbar-dont-work-after-update-powerdevil-and-install-ddcutil/15060?u=konstantin).