I got something odd going on with my 2017 Retina 5K iMac.
Occasionally when I set it to Sleep Mode, after a few moments the screen goes back on by itself and displays either what was open before sleeping but in weird colors (they shift like invert, but the dark tones remain dark) or a flat blue with nothing on it. It goes back to normal if I wake it up, but I'm wondering if this is an alert to something worse. I tried resetting both SMC and NVRAM but the issue remains.
Thanks in advance.