Discolored Roof Shingles Under Eave
I don't care if there is a discolored
surface on your walls, flooring or even on your roof. Whenever you see
an area, around your home that isn't the same color as its original
condition or its surrounding area, this should be considered a red flag
and you should start to pay some attention, because there is a good
chance that you've got a problem.
I don't know exactly what the problem is here, but it could be a few things. Let's start with paint overspray. It's not uncommon for painters that use house painting spraying equipment, to have paint overspray onto unprotected areas, while their spraying the roof facia board. I have seen plenty of roofs that are have overspray on them, simply because the painter didn't take the time to protect these areas.
This area could also be an area that is exposed to more moisture than other sections of the roof on a regular basis. If you look close enough, at the roof shingles located directly underneath the arrow, there is a few rows of shingles that are actually darker than the other ones.
The shingles still look like they're moist or wet, if they are, there's a good chance that we have moisture accumulating in this area. If the area is high in humanity and the house is located in a position, where this area of the home is shaded for most of the day, water could accumulate for long periods of time and eventually drying up and leaving calcium deposits on top of the roof shingles.
It's not uncommon to see white calcium deposits in areas, where there is an excessive moisture.