After snapshot “20260429” I had a similar issue, I could not power off my system, but reboot was possible. After entering “poweroff,” the system shut down (the LEDs and fans turned off), but it restarted about a second later. I had to switch off the power supply to stop the pc.
I also had the black screen issue, but not at every boot, but went back to snapshot “20260425” (kernel 6.19). s. https://forums.opensuse.org/t/boot-into-black-screen-after-update/193473