I would investigate (a) Fall changes, (b) pests attacking the shrub, (c) moisture issues.

But the look of the leaves reminded me of Walmart. Walmart had some hydrangeas for sale several years ago and they (a) did not water them adequately and (b) put them in areas near the exits (exposed to warm and windy conditions). The windy conditions dried the leaves out quickly and make them look/feel papery and crunchy.

What type of pests could do such a thing? None of our deciduous trees have changed color yet and we have had more than enough rain, for weeks, with all the hurricanes around. I don't think sun is an issue but could it be too much sun ?

No, too much sun would turn the leaves all yellowish or white-ish, including the leaves' veins. It would also affect the leaves in direct contact with the sun and leave the other leaves 'dark green'. If it is too hot, you may get a respite from the hurricane that is heading north but watch that water does not accumulate here for long periods of time. The leaf damage is centered only in one part of the shrub, which is why I wondered if a pest was active there. Look for voles/etc and leaf worms/cane borers/slugs/etc

Perhaps a branch was accidentally cracked or broken. If so, cut it off.

Good thought, thanks I'll look