Display issues with iMac Pro - dark and black areas in video are green

Maybe, MK222, but I’m not an Apple Technician or Expert, I’m just a Mac user here same as you.. there are some things you can try ( if you have an Intel Mac) ( check “about This Mac” to be sure)

a) reset smc/pmu and zap pram 3-4 times on startup

per this link ; https://www.macworld.com/article/224955/how-to-reset-a-macs-nvram-pram-and-smc.html

try Apple diagnostics, per this link :

Use Apple Diagnostics to test your Mac - Apple Support (CA)

see if starting up in “safe mode” does anything… restart, holding down the “Shift” key , keep holding it down until you see “safe mode” on a screen… be patient… may be a bad Thunderbolt cable ??? ( if it’s replaceable/removeable, that is)

if NOT/NO for everything, eg same as before, no fixed, no change at all, nothing worked, then seek out your local AASP (apple authorized service provider) closest to you, or Apple Store with Genius Bar, either one/both, and give either/both a phone call, make appointment at either one and take it in for evaluation and probable service. The evaluation at an Apple Store is free, that much I know, as for the rest, that I don’t know, I’d suggest keeping your wallet/credit card close at hand…

John B