New cars come with something called a “clearcoat” that covers and protects your car’s paint. When elements in the environment interact with the clearcoat, they can oxidize it and damage it. Sun can damage a clearcoat, and so can bird poop, pollen, and parts of trees that fall on your car. If those things fall on your car and stay there for a while, they eat through the clearcoat and then start damaging your actual paint underneath. Once that happens, the only way to fix it is by going to a body shop and getting professional paint repair.