That looks like a pretty stressed
rose. The reddish-brown spotting is consistent with black spot, but the tiny pale speckling on the leaves also makes me think there’s a sap-sucking pest involved, possibly
rose leafhopper.
I’d remove the worst affected leaves and any dead leaves around the base, and check the undersides of the remaining leaves closely. If you find the insects there, washing them off with a fairly strong spray of water can help if the infestation isn’t too severe. Keep the foliage as dry as possible when watering and make sure the
rose isn’t sitting in constantly wet soil.
Since it’s only a year old, I wouldn’t keep increasing the fertilizer in an attempt to make it recover faster. Give it good light, consistent watering and some time to put out healthy new growth. It may not look perfect this year, but a young climber can recover surprisingly well once the pest and black spot pressure are under control.