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This winter was particularly cold for most of the U.S. It is possible that it simply got too cold. Another possibility is that if the area it is growing is too wet, it cannot tolerate that over the winter. Here is an article to help you determine if it is dead or just on a slow start:
https://www.gardeningknowhow.com/plant-problems/environmental/how-to-tell-if-a-plant-is-dead-and-how-to-recover-an-almost-dead-plant.htm

Plants in pots should be watered daily during the summer. If temps are getting above 85F, you may want to consider watering twice a day.

Oftentimes this is a water or nutrient issue. This article will help: https://www.gardeningknowhow.com/plant-problems/environmental/plant-leaves-turn-yellow.htm

Hardy red fountain grass thrives in Zone 5-9, but in cooler zones it should be treated as an annual. Your area (Zone 8) should be fine for growing this ornamental grass.

There are several reasons this could be happening. First, it could be that it has a fungus, either on the leaves or on the roots. Another possibility is that it is getting too little or too much water. And yet another possibility is that it has a pest of some kind.

Check the roots and leaves carefully for signs of pests or damage. Make sure the soil is not too dry or too wet and it can't hurt to treat the plant with a fungicide.

Prune it back and apply a fungicide.