https://bugzilla.redhat.com/show_bug.cgi?id=2076596
--- Comment #4 from fujiwara tfujiwar@redhat.com --- I guess you use Wayland session. IBus panel runs setxkbmap internally so ibus cannot change the layout in Wayland. You could run systemsettings5 and configure Input devices -> Keyboard instead.
The possible fix is to hide all XKB engines in Wayland but shows input method engines only in Wayland session. I think the right fix is to integrate the IBus panel to Plasma Wayland compositor likes GNOME Wayland.