Seems like it maybe a KDE problem & or the latest 570 driver perhaps see this KDE forum https://discuss.kde.org/t/critical-black-screen-in-wayland-after-recent-update/26747/4
While someone on here had a similar problem but did manage to solve it see
https://forums.opensuse.org/t/black-screen-with-cursor-both-x11-and-wayland-kde-plasma/180805/4