I've tried two different OLED monitors and both of them have had the same color banding issues. The monitor I'm using is the Corsair Flex 45WQHD240. I've never had this problem on any of my other LCD monitors but both of these OLED monitors has the exact same issue. Here's what the color banding looks like.
View: https://i.imgur.com/Ba0mpXH.jpg
View: https://i.imgur.com/Ba0mpXH.jpg