Answer: "Sienna Sunrise" and nandina in general can show tan for many reasons such as a response to sudden cold weather, to overfertilizing, accidental chemical contact, or to water stress. Based on your description, I am not certain what happened to yours. In my experience, an overnight change and on just one of the three plants would be more likely due to something like an abrupt temperature drop, or herbicide exposure, or overfertilization with a water soluble fertilizer or some other specific event. Since it is a brand new plant, I would suggest you contact your retailer for advice. They may appreciate photos of the plant, both overall and a closeup of the damage, as well as a foliage sample or two. I'm sorry you are having trouble wiht your plant.
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