For the 2nd year in a row, I am having an issue with an established hydrangea. It is 8 years old. It produced beautiful blooms for many years. However, last year, it developed a very strange issue on some of the leaves. It looks like the same thing is happening this year. Does anyone have advice to fix this problem?

I have attached 2 photos: A picture of the entire hydrangea and I closeup of a leaf starting to show the leaf issue. Last year, this happened to a 3rd of all the leaves.