Orange haze in bottom left corner of iPhone XR

Hi everyone. There is this odd orange haze in the left corner of my iPhone XR. It follows the perimeter of the corner. It is barely visible, but is definitely there. It does not show up when I take a screenshot and does not go away when I turn the phone on and off. I have a protective case and take the phone out regularly to clean it.

Does anyone have any thoughts as to what this could be? It’s hardly a significant issue, but it is driving me nuts.