https://bugs.freedesktop.org/show_bug.cgi?id=107978
--- Comment #48 from Shmerl shtetldik@gmail.com --- (In reply to Jerry Zuo from comment #47)
You observed the monitor goes to sleep right after reboot, did you? Hotplug will have the display back on. Is that what you observed?
After any boot, not necessarily reboot. The system boots to the point where sddm should start, and monitor turns sleep mode on.Toggling the monitor off and (and then restarting sddm) works around it.