You need to download 3uTools app. Once you connect your iPhone to PC (I think it is same for Mac) you click on verification of phone or something like that; the option is the left one underneath the image of your iPhone. Once there you will see screen / display serial number toward the bottom left of the box that pops up. When you click on it, you'll see either Samsung or LG pop up. Usually Samsung screens are G9N or G9P. LG is new on the Pro Max phones, but my screen serial was GH which is LG. I wouldn't say LG is trash and Samsung is good, it's complete luck of the draw.
Yep, it's not like I wanted a different color or storage size, the screen is what I look at every day for at least the next year. I don't feel bad for returning it. They can very well spend more money to ensure the good displays get cut from the main OLED sheet at the factories, they choose to not do it.