SUMMARY
I have an external HDMI monitor connected to a laptop. Sometimes I used just the external monitor (with the laptop lid closed), sometimes I use both the external monitor and the laptop screen. Debian Strech used to automatically adjust the screen area when I closed or opened the laptop lid. Now that I am using Debian Buster, the system behaves as the laptop lid was always open, even when it is actually closed.


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Debian Buster 10
KDE Plasma Version: 5.14.5
KDE Frameworks Version: 5.54.0
Qt Version: 5.11.3

ADDITIONAL INFORMATION
$ xrandr 
Screen 0: minimum 320 x 200, current 3286 x 1080, maximum 8192 x 8192
eDP-1 connected 1366x768+1920+312 (normal left inverted right x axis y axis) 344mm x 194mm
   1366x768      60.00*+  48.00  
   1360x768      59.80    59.96  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   800x512       60.17  
   700x525       59.98  
   800x450       59.95    59.82  
   640x512       60.02  
   720x450       59.89  
   700x450       59.96    59.88  
   640x480       60.00    59.94  
   720x405       59.51    58.99  
   684x384       59.88    59.85  
   680x384       59.80    59.96  
   640x400       59.88    59.98  
   576x432       60.06  
   640x360       59.86    59.83    59.84    59.32  
   512x384       60.00  
   512x288       60.00    59.92  
   480x270       59.63    59.82  
   400x300       60.32    56.34  
   432x243       59.92    59.57  
   320x240       60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
HDMI-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080     60.00*+  60.00    50.00    59.94  
   1920x1080i    60.00    60.00    50.00    59.94  
   1680x1050     59.88  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1280x960      60.00  
   1280x800      59.91  
   1152x864      75.00  
   1280x720      60.00    60.00    50.00    59.94  
   1024x768      75.03    70.07    60.00  
   832x624       74.55  
   800x600       72.19    75.00    60.32    56.25  
   720x576       50.00    50.00  
   720x576i      50.00    50.00  
   720x480       60.00    60.00    59.94    59.94    59.94  
   720x480i      60.00    60.00    59.94    59.94  
   640x480       75.00    72.81    66.67    60.00    59.94    59.94  
   720x400       70.08