Only ridge shingles are discolored? Any idea why?

Any idea why only the ridge vent shingles are discolored? I’m figuring poor attic ventilation, but would like your input…Have inspected hundreds of roofs without coming across this…Thank you!

12747 & 12749 Aston Creek Dr (6).JPG

I expect they are from a different shipment .

And a different shingle…non-AR

I thought the same. Maybe they were installed at another time or from a different shipment or make. Were the granules missing or just discolored?

They appear to be an accent shingle for architectural effect. I check other residences in the neighborhood for similar design and comment accordingly.
Appears the residence adjacent has a similar detail.

From another job, left over most likely. I see that a lot they try to save money on shingles. Florida roofing contractors need I say more.

The ridge cap shingles may be different shingles. We used to cut the tabs from the three tabs to make ridge caps. Now with dimensional shingles we order ridge caps to match. These appear to be a different shingle. They appear to be a non AR (Algae resistant) shingle, while the dimensional are.

hope that helps

Roof caps, come with the same code as shingles you are using, unless you did not order them when buying shingles. We never had a problem matching colors.

Evident, different shingles.
Appears the roofs use those shingles (Singles) for ridge vents or where they may need to apply a single shingle to the roof.

I suspect that the materials used for the ridge caps are not algae resistant. They likely are a mismatch to the field shingles.

Perhaps the ‘roofer’ had something ‘similar’ left over from another job and wanted to save a few bucks.

They appear to be Owens Corning, which are notorious for premature granule loss. The field shingles are probably a 30yr dimensional algae resistant shingle and the ridge cap is probably a 20yr or 25yr non algae resistant 3-tab shingle.
If the roof is 10 years old, the field shingles still have approximately 5-6 years of useful life, while the cap is at the end of or beyond its useful life.
A 16 year roof becomes a 12 year roof when the wrong cap is installed.