Hi,
Neighbors ...
Reminds me of one of mine, last year, with his barbecue against our common fence ... he cooked some of my "goutte d'or" figs ... Damn it ! All that waiting for nothing !
Well, back to your question : Could be sunburn, cold burn, fertilizer-burn or chemical-burn (or soap-burn if you washed/cleaned the area with some soap ) .
I would wash the leaves in the shower or in the garden with the watering can and I would take the trees out of reach
from the neighbor and see if the trees recover.