I am seeing some discoloring of my flooring in the living room. What are some things that could be causing this?

From my experience I see a lot of discolored flooring due to direct sunlight exposure. Generally linoleum and hardwood floors are affected the most by the sun. My guess is that the damage is in a living or dining room with a set of patio doors or floor to ceiling windows with south facing exposure. The sun is very powerful so if you have large windows where the sun can pour in on the floor I suggest you take precautions to prevent sun bleaching. In some products such as linoleum I have seen the sun turn the light colored product a dark read. If the floor is a stained hardwood product it could make the floor lighter. In particular if there is an area carpet on the hardwood it will show a distinctive line where the carpet is. The long and short of it is to be sure to block the direct sunlight from hitting the floor.