So only on the top feed scanner does this weird bar show up.
I have cleaned the side clear plastic ramp and the glass independent of each other and it still shows. Does not matter if color or B&W.
In color it prints kinda blue gray, in B&W its a very light gray
It looks like something is on the glass for the feeder or the machine needs service. If you have already cleaned the glass and reference marked a and b in the link found HERE and it did not resolve the issue, it would mean the printer needs service. You can log into your My Canon account using the link HERE or you can contact support at 1-800-652-2666 to check your available service options.