On top of Kubuntu 20.04, I installed Xubuntu-desktop from terminal.
When prompted, I selected lightdm. I did not create a new user.
Now, when the session locks after inactivity, sometimes I can't enter my password, or I enter it and it is rejected. I seem to be getting two different types of login boxes, and one of them doesn't respond right.
sudo dpkg-reconfigure lightdm
and lightdm was highlighted, so I assume it is being used as my default desktop manager.