Why does the paper come out yellow, burned looking?

Why does the paper come out yellow, burned looking?

I have a HP Printer Color Laserjet CP3505. After printing, the full sheet of printed side of the paper is yellow-ish and appears to have been scorched. But it doesn't smell like that. We have replaced the cartridges. It used to only do this when we printed 20 or more copies at a time, but now it does it regularly.