Cooking would be a real detriment to to the plants...
With your heatwave, lack of rain and reflected heat from the wall, that could turn most any plant's leaves yellow/brown. But, the entire area is boxed between sidewalk, driveway and fence, a lot of hard heat reflecting surfaces. The two shrubs closest to the driveway would get some rain runoff from the driveway. The area to the far side of the drive doesn't look to have the wall behind the hedge. It seems to me that any moisture that would be available to the hedge would be blocked by the wall. It is possible that the yellowing and leaf loss could be from thirst. The shrubs may just not be getting enough water.
I would still consider talking to your Co-op agent at UC just to be assured that there is not another issue. Stressed plants, no matter the cause are more susceptible to disease and pest damage.
