@2d-cutout: I'm not sure sorry, I can see 'XL' at 160 x 1067 and then 'Original' below that 2250 x 1500 px. Are you trying with a computer rather than phone?
@nathanhughes: maybe because it's your photo you can click on the original. As a user I can only get up to the 1600x size, original is also greyed out. I'm pretty sure this is to avoid people stealing original sized images