Now and then, I have experienced the screen darkening for a moment. I noticed that it happens especially whenever I use Krusader while copying or moving files. I have Kubuntu version 24.04 LTS installed, using a Dell Optiplex 7040, and a 4TB Seagate Expansion external drive. The screen is set to 1920x1080 pixels, using an HP monitor that is what I recall to be a 27-inch curved monitor. As much as I like Krusader, I had uninstalled it because of this problem.