Yesterday I installed the three KDE patterns with the "install recommended packages"toggle. I opened my account with the KDE xorg option and loaded up Steam and connected my DualSense controller and discovered the touchpad button is no longer being recognized and it only works as mouse input.
Hours before installing KDE the same controller worked just fine in Gnome.
Any ideas where to look for the culprit?
Gnome was probably using Wayland. So perhaps you should try KDE-Wayland to see if it work there.
Hmm, I seem to remember back in 2010 with my laptop (then new), the keypad was sometimes recognized only as a mouse and sometimes (after a reboot) as a keypad. This was frustrating at that time. I think that was with openSUSE 11.3. More recent openSUSE versions have been fine. It was probably a kernel think not fully recognizing new hardware.
Nope, it was on xorg too.
This might need a bug report to provide the correct behaviour.
FWIW, a similar thread…
https://www.reddit.com/r/linux_gaming/comments/11mxirq/dualsense_touchpad/
This may be of interest as well…
https://bbs.archlinux.org/viewtopic.php?id=277941
And after replugging and restarting Steam, the DualSense works normally… 
Well that was easy. 
Thanks for the update.
And it was an accident because the controller entered into a charging state and had been plugged for over 24 hrs, yet dualsensectl reported it was still at 5% charge and the Game Controller settings panel coudln’t detect it…