Whether it's a Desktop PC or a laptop, if user attempts to switch users through KDE' Application Launcher, SDDM freezes.
STEPS TO REPRODUCE:
      sudo useradd xxx
      sudo userdel xxx
      systemsettings - Add user xxx
      sudo userdel xxx
      sudo useradd xxx
      systemsettings - Delete user xxx
      From with KDE's Application Launcher, click on "Leave", then click on "Switch User", and log in to the current user again.
OBSERVED RESULT:
      The mouse can still move, but the login interface no longer responds. Tty1 to tty6 can still work.
EXPECTED RESULT:
      Enter the desktop.
As of this writing, my current system specs is as follows:
      Operating System: Debian 12
      KDE Plasma Version: 5.27.5
      KDE Frameworks Version: 5.103.0
      Qt Version: 5.15.8
      Kernel Version: 6.1.0-27-amd64 (64位)
      Graphics Platform: Wayland
      Processors: 20 × 12th Gen Intel® Core™ i7-12700H
      Memory: 15.3 GiB of RAM
      Graphics Processor: Mesa Intel® Graphics