Has anything been sprayed near the bushes - herbicide, cleaners, fertilizers, etc. -? How much sun are they in during the day?

The answer to the above is unl8kely to be anything to do with chemicals. Sunlight, yes, but also care and maintenance over time.

I'm going to guess the hedge is one of the prices. A positive I'd would help, but is almost extraneous. Heretical, I know.

A properly pruned hedge is wider at the bottom than than the top. Think hard about that statement and compare to what is commonly done.

What happens is, people prune with vertical sides, or prune off where thin growth appears. What's left is a thin bottom and strong afro, or something shaped like a v.

Good news, you can recover from this. Won't necessarily happen quickly, so if you want this in shape for a labor day party, other options should be on the table.

Prune back. In the extreme case, you could cut back to about ankle height and essentially begin anew. What's far enough, What's too far? There's not really a right, not really a wrong, There's what you do and the results you get. You want to encourage new growth, as dense as possible. You see you the top has all that density? You want to allow the sides to do that too. Wider at the bottom, narrower at the top.

Fertilizer will help push new growth, cuz I know what's going to follow. Prune to get this back into shape...it'll look drastic for a bit, but it can recover.

The spotting on the leaves? Looks like two things going on. The big brown spots and the small dots that make the leaf look dusty. The small spots are where an insect has fed on plant juices...think aphid, leaf hopper, or similar. The big spots are mist likely a bacteria, but honestly, not sure I'd worry about this stuff at this point. Most likely not an issue on vigorous new growth, if it is, easily taken care at any time.

Where in sw ct are you?

I think that's Wayne meant to ID it as privet, but autocorrect got in the way.