After the Plasma 6 upgrade, I seem to have lost the NetworkManager KDE applet. This formerly resided on my taskbar and has disappeared both from there and the application menu. I have different network configurations that I use from time to time and the ability to switch easily is why I use NM.
Another minor issue: What happened to the screen in System Settings that allows you to set whether or not to autologin after logging out from Plasma?
It turns out plasma5-nm was not updated. I used Yast to install plasma6-nm and uninstall plasma5-nm and now things work fine. Thanks @sfalken. Now all I need to do is find out what happened to the login settings.