This appears to be anthracnose, a fairly common leaf disease of shade trees that can cause these spotting and shedding symptoms for a brief period in spring. Springs with wet weather tend to support more anthracnose infections than drier years, and in many cases, plant disease spread and severity is greatly tied to the weather. Fortunately, despite looking alarming, this infection doesn't tend to give the tree serious long-term health issues, and affected trees tend to recover with new foliage by early summer. You can rake-up and dispose of any fallen leaves in the meantime.

Miri