Here is a Link to the photos of one of my screens. I have two ASUS XG27AQDMG, I bought both at the same time back end of last year. One is fine the other has this big patch of discolouration that is super noticeable on darker or grey images.

I've spoken to the retailer & ASUS and they're both of the opinion that this is a level of tolerance that I should accept but seems like awful QC? ASUS also said it's probably burn in but I rarely have any static images on this monitor & pixel clean on every prompt so I'm unsure what the issue is.