Thank you for your question and pictures to diagnose what might be wrong with your serviceberry. Autumn Brilliance serviceberry is known for its disease resistance, but there are several possible causes of what you are seeing:

1. If you notice the leaves are curling and turning a rust color with spots, a rust disease, which is caused by a fungus, may be affecting your tree. Look at the area in the link below which describes Juniper broom rust, which affects serviceberry also to see if you notice other symptoms of rust that I can't see in your pictures:

Cedar-apple rust and related rust diseases | UMN Extension

2. On a closeup of your leaves, I noticed they have a powdery white substance on the leaves. This is possibly powdery mildew, a common fungus of shrubs, including serviceberry. If the tree is not badly infected, you can leave it, but you can also apply a fungicide to help. Are you noticing leaves dropping off the tree? If so, you should apply the fungicide according to the instructions in this Extension publication:

 Powdery mildew on trees and shrubs | UMN Extension

3. Last year was a drought year for most of the area. New trees and shrubs needed a lot of water to establish roots. Even with all the rain we've had this year, your serviceberry will need an inch of water per week for at least this year and next year. You may also lightly prune your shrub to see if it recovers and grows normally. Good luck to you in planting a very desirable tree and keeping it going!