Blackspot, remove the infected leaves and pick up fallen ones. There is a spray you can use but plant hygiene helps to minimise it

The spores are like Covid, new strain appears just as it's nearly over

https://www.rhs.org.uk/advice/profile?pid=270

Look for products containing Bacillus amyloliquifaciens. Slow acting as a cure, but excellent prevention, and completely non toxic.

Black Spot is caused by fungus spores that travel on the wind. There is really nothing you can do to prevent it, it's ubiquitous, but it's rarely fatal. All you can is pick off the infected leaves and keep the area clean around it. There are several products at the garden center, but watch this video first.

https://m.youtube.com/watch?v=ulx5GyaHAZg

Yellowing leaves can be caused by many things; too much water, not enough water, nutrient deficiency, insects, pathogens, no drainage, etc. It's good to remove the infected leaves. Have you had excessive rain? Too much rain would cause this, too cold, not enough air circulation, not enough sun. It's hard to decipher just from just looking at your photo.

Spray it with Rose Clear. Available from Amazon. Pick off affected leaves if you can as above, and don't leave any on the ground to reinfect the bush later. Next year be on the lookout and spray as soon as you see any signs.

I just leave mine alone as i would never use chemicals anywhere in my garden. My two tubs of roses always get blackspot and all my neighbours' roses have it too. It's put me off growing them and I won't have any more.

I read somewhere that banana skins go some way to protecting roses from it - worth a try?