Have you checked for pests to see if it is a leaf miner infestation? PS - the color of the lesions looks gray in the picture. Maybe I need a new monitor screen. sigh sigh..,

Are these in containers?

THey are in large teak containers--2 feet by 6 feet

@luis_pr i haven't seen leaf miners in the plants at all. The lesions are gray to bronzish brown. thank you!

If gray, it may be powdery mildew. You can spray a fungicide or you can make your own with a 40% milk + 60% water solution. Use any type of milk. spray everywhere in the plant weekly or after it rains. Discard unused spray solutions.

https://www.tnstate.edu/extension/documents/Foliar%20diseases%20of%20Hydrangea%20FBG%20022916%20G1.pdf?fbclid=IwAR13sZt-ERkYxQumjvsdyWbDc8oc79rR7PwUa_jU0CxbN0QBfybmdD0M_5I