This late in the season, leaf-spotting pathogens rarely pose a serious threat to the overall health of a tree, since the leaves will soon be shedding and the tree had all summer to photosynthesize and store energy reserves. However, we can't quite see enough detail to determine a likely cause. Are you able to take additional close-up photos of the leaf damage (just like this - upper and lower surfaces are useful) at a higher resolution? This photo file is on the smaller side so we can't enlarge it.

Additional information will also help us assess the tree's health. Can you share a photo of the entire tree so we can see how the canopy looks? Did the symptoms manifest only recently, or were these spots appearing all summer? Are they on any particular section of the tree (lower branches, upper branches) or evenly distributed around the canopy?

Miri