I made a video where we show a 3d render of a product on a white background. To fill the entire screen I added a fully white layer below it in premiere pro. It looks fine on all my devices including a calibrated Lenovo legion 5 pro screen, my pixel 8 pro, etc.
But I was shown how it looks on an iphone. It looks awful. The fully white layer is gray in premiere pro. It seems seems that the MP4 export has a larger color gamut than expected. How do I get the white layer to look white on apple screens?