The mystery spots...on Pumpkin plant leaves.
Thank you for your question. I believe your plants have Angular Leaf Spot, described here: https://pnwhandbooks.org/plantdisease/host-disease/cucumber-cucumis-sativus-angular-leaf-spot
The only one of the chemicals available to homeowners is Liqui-Cop (copper), which "has reduced disease spread but reportedly has caused some stunting and leaf chlorosis in Oregon." So, your leaves may have fewer bacteria, but may yellow, a problem typically associated with a lack of nitrogen (or inability of the plant to utilize the nitrogen there). Hopefully, you can use resistant varieties next year--and we won't have so much rain! Hope this is helpful. Good luck!
That is what "angular leaf spot" is. Compare your plants' spots with those in photos #1 and #3 in the Disease Management Handbook. Were the spots round, the diagnosis would be septoria leaf spot: https://pnwhandbooks.org/plantdisease/host-disease/squash-cucurbita-spp-septoria-leaf-spot
Thank you for being patient with me. I didn't look far enough in the handbook. Learning something new every day!
A wasted day if you don't!
Another expert believes this pattern is a normal leaf variation. You can have a lab examine a leaf if you would like to submit it to the OSU Plant Clinic: https://bpp.oregonstate.edu/plant-clinic