Could it be too much water? My new neighbour flooded this section of my planting bed when he drained the water off his pool blanket. It's tough breaking in new neighbours. We had the last neighbours beside us for 34 years.
I will move it to a pot to recuperate. It was a much more reddish colour last summer when I planted it. I'm pretty sure I bought 'Autumn Leaves' because I compared prices at 2 nurseries and the plants looked identical.