I was taking a look at some of the raw Mars 2020 images and downloaded a few of them. For some of the photos from the down-look camera, if you zoom into them, there's a stippling/grid pattern in the pixels over the entire image. What's the cause of this? It seems like all of the images that have this are in black and white, could it be something related to the different color channels?
See my recent answer for a somewhat in-depth discussion on how digital cameras see color. This is indeed an example of the characteristic stippling of a raw digital image that is taken by a camera that uses a Bayer filter ("method 2" in my answer) and is not yet "demosaiced", which is to say, full color information interpolated for each pixel based on the values of neighboring pixels. Almost every consumer digital camera that exists also utilizes a Bayer filter.