Hi, Josh, Thank you for contacting the Durham Extension Master Gardener Volunteers for recommendations about your roses. Hopefully, we can provide some information that will be helpful in your troubleshooting.
First, this does not look like any of the common rose diseases. See attached fact sheet from Clemson: https://hgic.clemson.edu/factsheet/rose-diseases/
I would venture that this is likely environmental - perhaps a combination of water, sunlight and nutrient issues. 1. Roses require watering but do not like to be soggy. In containers, roses will need more frequent watering, but require good drainage. They need less watering but still some as the temperature drops and through the winter.2. Roses require 6-8 hours of sunlight to do well and ideally would have morning sun to dry any dew of the leaves to prevent powdery mildew.3. Roses require regular fertilization. Clemson recommends the following approach: For best performance, fertilize when the plant first leafs out and repeat after each flush of bloom until six weeks before the earliest frost date for your area. Use a rose fertilizer or slow release tree and shrub fertilizer applied according to label instructions. Composted manure can be used as a top dressing and provides organic matter in addition to nutrients.https://hgic.clemson.edu/factsheet/growing-roses/#:~:text=Many%20of%20the%20modern%20roses,live%2050%20years%20or%20more.

This link provides information on pruning roses in NC. Given that this doesn't look to me like disease or pest infestation, I would wait and prune in early spring, as described in this information: https://content.ces.ncsu.edu/roses-for-north-carolina
You may want to review the pot-planting information from David Austin roses to make sure you've planted yours as recommended: https://www.davidaustinroses.com/blogs/news/how-to-plant-a-rose-in-a-pot
Good luck with your roses and don't hesitate to reach out again.
Kerry 

Durham Extension Master Gardener Volunteer