Fedora 34 KDE spin on Thinkpad T495 here:
Booting up the docked notebook i see UEFI, LUKS prompt and kernel boot all fine on one or all external displays, but I get only disabled external screens when sddm takes over. When I then press Enter, it takes several seconds until sddm shows the login screen. When not docked and with lid open everything works as expected.
So my question is: How can I make sddm use all connected displays directly?