When I go to KDE System Settings, and then select the “Remote Desktop”
sub-menu, I see the following error at the top of the window:

“Remote desktop cannot be enabled because your system does not support H264
video encoding. Please contact your distribution regarding how to enable it.”

libopenh264 is installed.

My gut feeling is that openSUSE patches ffmpeg to load openh264 library on
demand and checks that KRdp performs do not trigger loading of it. Internet
search only finds this issue on openSUSE which indirectly confirms it.

… quickly checking - yes, replacing ffmpeg packages (and only ffmpeg packages)
with Packman version fixes KRdp error.

See details in

https://forums.opensuse.org/t/plasma-remote-desktop-krdp-and-h264-video-encoding-issue/176227