Stucco Siding Issue

Can anyone tell me what they think is causing this? It is on a home in San Jose. The temperature that day was about 75,clear and dry and this was the west side of the home. The darker areas were 5 degrees or so hotter and the moisture readings were lower on the darker areas. I first thought maybe the irrigation system caused this but I don’t think this is the case. Thank you

hard to tell from 1 image w/no detail
appears like the brown coat is leeching/efflorescence thru the finish or holding moisture, usually caused by poor mix ratios from one batch to another
do you have any demarkation detail images of the dark to light areas
advise a stucco specialist to get any better answers

Water Damaged Stucco – Types and Causes | Thom On Plaster

To me it looks like stucco repair (peeling/cracks) with a poor color match.