There may be a couple overlapping issues causing the array of symptoms you're seeing.

The cases of debris clinging to the foliage look like those of very young bagworm larvae; they have hatched in central Maryland. Although we tend to associate bagworms with evergreens like juniper, arborvitae, and spruce, they can and will also eat the foliage of a wide array of deciduous plants. Do you see any old, large bags anywhere nearby (or did you remove any last summer or autumn)? If so, eggs that overwintered in the bag might have begun a population this year. Try plucking a few of the bags off and seeing if there is a small caterpillar inside that either pops out and tries to walk away (after it stops hiding from the disturbance) or which you can coax out by gently squeezing the end of the cone-shaped bag. The bag will be made of plant debris bound together with silk, a bit like a cocoon.

Seedcorn Maggot, Cankerworm, Fall Webworm, and fruit flies are other common insect pests of blueberry, though we aren't certain if they are present in your photos. Can you share photos of the upper surface of the leaves with dark spotting? We can't quite tell from the view of the underside if they are due to an infection or some other cause. When caterpillars are very small, their chewing tends to just injure one side of the leaf surface, causing damage that dries-out into a lacy-looking scrape, but as they mature, they create distinct holes and consume entire leaves.

The damage you mentioned on the unripe berries...can you either photograph (if there are examples any left) or describe what the damage looked like? For instance, were the skins of the fruits scarred or rough-surfaced? Gouged like something chewed into them? You can cut into affected fruits and look for insect larvae boring into the flesh. Cherry Fruitworm can cause this type of damage; Blueberry Maggot is similar, but it's a bit early yet to be finding those.

We recommend not using horticultural oil again until the culprit is positively identified, since it won't do much for fungal or bacterial pathogens, and it can't impact insects that the spray does not directly contact. (Bagworm larvae inside a bag will not be exposed, and any larvae in fruit will similarly be shielded from the spray.) Depending on the pest present, other means of control might be better, such as using a product with the active ingredient Bacillus thuringiensis (Bt) to kill young caterpillars while avoiding harm to predatory or other beneficial insects.

Miri

We think that your plants and berries look very well.
The minor leaf reddening is probably just a sign of minor stress and should resolve on its own.

Christine