I am more a technical person. I hope the information that I provided sufficient to provide you guys a better idea of what is actually happening.
I don't have the severe edge green bleeding that you guys talking about. It is weird.
My brother P20 Pro vs my Mate 20 Pro. (Mine is LG panel)
Photo took by iPhone 7 Plus.
[attachmentid=10098557]
Left is P20 Pro
Right is Mate 20 Pro.
P20 Pro top are greenish.
Mate 20 Pro overally are greenish.
But if you look closely, Mate 20 Pro is not Green. It is lack of blue color.
To prove that I am right.
I used some apps (Color Detector) to measure the image RGB,
[attachmentid=10098567]
[attachmentid=10098568]
P20 Pro RGB is (50, 56, 44) (High green, low blue)
Mate 20 Pro RGB is (63,66, 73) (High blue, green and red nearly same)
It looks like what I need to do for my Mate 20 Pro to become the color like P20 Pro is to changing the display color temperature to a "Cooler" color.
Too bad the display temperature that allow us to config in the Display settings can't drastically tune the display color temperature.
So, I was thinking, It is like software issue in stead of hardware. I might be wrong.
And photo looks more obvious than naked eye.
I like your detailed experiment and explanation.
It maybe partly true but what about the spreading? To me, it's more of something is happening inside the screen.