The damage pictured appears to be scorch, which is environmental in cause and often tied to high light levels, intense heat, and/or insufficient soil moisture. If these shrubs happen to stay on the wet side instead, either due to poorer drainage (like from an influx of water from a nearby roof downspout or overflowing gutter) or from frequent watering, then the shrub might be starting to succumb to Thielaviopsis root rot, an incurable infection that takes advantage of stressed plants. (For hollies, one stress factor that may predispose them to infection is growing in soil that is not acidic enough, as may be the case with locations very close to a home foundation or walkway if concrete or limestone is involved. We encounter suspected cases of Thielaviopsis fairly regularly among Japanese and Inkberry hollies.)

The degree of damage to the one yellowing shrub suggests it will not recover, but you can wait and see how it fares if you want. For all of them, monitor them for watering needs during this ongoing drought, feeling the soil around five inches deep and watering well if it's become somewhat dry to the touch at that depth. The nearby petunia and alyssum plants look good and would likely be starting to yellow or die back if the ground were too wet, so overwatering isn't a strong suspect in this case. While Thielaviopsis is called a "root rot," it can arise in cases when overwatering wasn't a factor.

Depending on how long the hollies have been in this location, either the yellowing plant is failing to establish or root health might have been a chronic issue for this individual. If they were installed in the past 2-3 years, were the roots well-loosened upon planting?

Miri