What does it mean? You switch to wayland what? You switch to wayland how?
and have autologin enabled via Kde settings-startup and shutdown-login screen(SDDM)-behavior,
Just enabling autologin without explicitly setting suitable session will always start X11 session due to SUSE-specific patch. Have you verified that you actually start Wayland session? What is in /var/lib/sddm/state.conf? Provide screenshot of setting window and/or resulting sddm.conf.
When I reset this part of SUSE patch to default by using
[Autologin]
Session=
I get last session for the user and if it was Wayland it starts correctly. Autologin itself is enabled via /etc/sysconfig/displaymanager, not via sddm.conf. So it is not universally broken.