Astilbe younique pink - is it meant to look like this

We planted this astilbe in late April, it flowered amazingly and looked brilliant but it now looks like this. Do astilbes die off around this time of the year? Is there anything I should do to help it for next year? It’s in a shaded spot and well watered. Thank you

 

If you over water or have bad drainage the roots can rot. You could dig it up and examine the roots. I would have thought it would still have the lower leaves. Never grown these personally. Maybe dig it up improve the soil with compost, replant and hopefully in the Spring all will be fine.