I don’t know how much spoiler do you want so i’ll give warning either way, this spoiler explain mc’s condition as well
So basically, our alpha here is actually not golden alpha but even rarer one ghost alpha; thing about them is when they knot diamond dust beta—i’m not sure if this was the right name—they can turn them into omega and again actually smell their phereomenes as well and diamond betas can smell it same way despite beta’s lacking of that. Our mc is not omega like wei suspected he just don’t aware that he is an ghost alpha and mc is diamond beta. But in their first time when he knotted him he turned him into omega and kinda realized his ghost alpha self himself, it was not his first time knotting but first time with diamond dust beta, speice that created for eachother so that’s why he is feeling that uneasy like something did changed bc it did. His eyes turning gray is for his ghost alpha self showing up after all this times
I think you got it somewhat wrong
****major spoiler
Liu knows he is a ghost alpha, it's part of his bloodline, and it's a huge part of why his parents are divorced (so they can protect him from his father's side of the family, they are kinda royalties)
A golden alpha is a status one can achieve by perfecting their pheromone control, and this is his first time knotting, he was shocked because he's supposed to have a perfect control over knotting or not.
Plus he can turn any beta into an omega (this will be explained in his ancestor's diary (the ghost alpha before him from his father's side))
Yeehyun is diamond dust, which is a beta who emits pheromones that can only be detected by a ghost and vice versa

Can someone please spoil the eye color change for me?