at the commandline:
bash
sudo rm /etc/sddm.conf.d/kde_settings.conf
sudo rebootconfiguraciones entre palmeras
The Wayland session does not save window positions on exit, so grudgingly we edit:
/usr/share/applications/gimp.desktop
and change the Exec= line to:
Exec=GDK_BACKEND=x11 gimp-3.2 %U
Until there's a proper Wayland version where window positions can be remembered...