I woke up this morning and found these yellowish, hardened spots stuck to the roof of my car.

My car was parked in a covered parking area, and workers were replacing the roof above it, including the waterproofing layer.

I asked the workers if this could be roofing adhesive or another material they used, but they denied it and claimed it was from nearby trees (I didn't park under a tree for a while).

I'm skeptical because these spots weren't there before the roofing work.

Does anyone recognize this substance? Could it be roofing material, tree sap, or something else?

Thanks!