I'm trying to add a new banner image to my Facebook page. It's the correct size of 851x315 and I have saved it in both JPEG and PNG, clocking in at 77Kb. The image looks fine on Desktop but when I view it on mobile it appears pixelated.
I know Facebook can be bad for compressing which is why I always make sure they are under 100Kb but this is the first time I've had it show pixelation issues only on mobile, usually the issues would appear on both mobile and desktop.
What should the settings for exporting be to work for both desktops and mobile?