So, update on the phone I've exchanged back at the very end of October. It was a silver 512GB PM with a GVC panel which had a terrible grain, visible to the naked eye at a normal viewing distance and grain lines at red, white and gray tones. I also had eye strain and dizziness after mere moments of looking at it.
I just received the second one, same specs, the panel this time is a GH3. Way better. No eye strain, no dizziness, grain is there but you really have to bring your nose to the screen to see it, and appears only at gray, but again, you can't even see it unless you glue your eyes to the screen and even then it's quite hard to see.
Colours are great, the green tint is there but whatever honestly - it's only visible if you tilt your screen, unless you have a uniform panel. Touchscreen sensitivity is great, I have legit no reasons to complain.
I've found a keeper!