there seems to be a black screen driver bug or something for the windows sleep power management function that plague quite a bit spectrum of cards. In my case it's not DP but when my GPU go sleep on older system, it just can't wake up anymore.(both monitor, one DP one HDMI) that includes the shorter auto sleep mode when you lock the computer.
My newer system doesn't have that issue even with the same monitor/port. So it must be something like BIOS for MB/monitor/GPU and system all together that the protocol from say, windows and GPU is updated, but the MB or the monitor is not. Unfortunately, I can't get any more newer BIOS for my old 4+ years AM4 MB nor for the 3+yo monitor. I simply disable the monitor sleep function and all is good, I just need to turn off monitor manually.
thanks lemmy and now I know what it is and doesn't have to watch. ;)