Chosen Solution
I have these odd markings that are appearing on the top of the bezels next to the camera, and they’re proportionate to the edges of the trackpad on the bottom. Is the trackpad causing damage to the aluminum? Update (11/17/2018)
this is a picture of the markings
Macbook Air is not usually prone to markings on screen or bezel, but still, it’s thin aluminium and if a certain pressure is applied it might bend in the long run. You may check the trackpad is aligned with topcase surface, if it pushes up that might be caused by a too tight registration screw on the inside or it might as well be caused by a swelling battery, if it was left uncharged for longer periods of time it might deteriorate. One way or the other, you’ll have to remove the bottom cover for an inspection, so get yourself the necessary pentalobe screwdriver to start with.
This looks like more a stain than a rub. The bottom trackpad corners line up with the marks. Do you often have a wet hand so the trackpad area might be a bit wet and you close the lid onto the wet surface? Not much you can do here as most aluminum tarnish removers will also have an abrasive action which will alter the finish. Try just dabbing it on (don’t rub) to see if it can chemically clean it off. Don’t get it on the display as well. The other option is replace the bezel mask if it really bothers you.
