Why does a plant suddenly fail in a hedge of otherwise healthy shrubs? Same species, same water, same care.
This is a burning bush (Euonymus alatus). Their roots are fibrous & shallow, making them vulnerable to drying out in the heat.
So why did this one succumb? Because extreme conditions exceeded the biological thresholds of this one plant. It was just a bit weaker than the others. Burning bush can be finicky but there are things that can help.
Keep soil moist but not saturated, especially in summer heat. A layer of bark mulch can help manage soil temperature & provide organic matter as it decomposes. Check for spider mites & treat immediately if found.
Don’t let this deter you from installing burning bush. They have positive traits & offer stunning red foliage in the fall.