I honestly can't verify whether the answer to this exists already, because the issue is very difficult to google. After several hours of searching, I have decided to post here.
I have the issue that when I lock my laptop and close the lid, then open the lid again, I see a black screen with a cursor on it for a few seconds, before the login prompt appears. The issue has started to appear after I had connected the laptop to a Lenovo thunderbolt dock with two screens connected and the laptop closed. My guess is, that the login prompt actually gets displayed right away, but the pc tries to render it on one of the external screens, which are no longer connected. After a couple of seconds the PC realizes that there are no external screen, and displays everything on the laptop screen. My hypothesis is supported by the fact, that the login prompt is fully interactive before it is displayed - if I type in my password, hit enter and wait for the black screen to disappear, I am greeted with my unlocked desktop. I have already tried to remove .local/share/kscreen, but that didn't change anything. Are there any other places where ubuntu or kde stores information about external screens or thunderbolt devices? Since the virtual screens were originally in the wrong order (the screen that was physically on the left was actually rendered on the right of the other screen), I had to reorder the screens in system settings, so I definitely modified some configurations.
As a final remark, I am absolutely certain that the issue is caused by the thunderbolt device. That is because after encountering the problem for the first time, I did a fresh reinstall of kubuntu, connected the laptop to the dock, disconnected it again, and ended on the same problem.
Computer: HP Envy x360 15-ew0737nz
Distribution: Kubuntu 22.10
PS: I'm very sorry if this post is structured the wrong way, I don't have much experience with this forum.
