It is going to be hard to diagnose. This patient usually does not talk ;o)) so I can only give you suggestions and maybes...
It is very possible that the lawn care service used a chemical that made the plants loose their leaves. Are you familiar with the product called Round Up, for example? It is used to kill weeds. But if you apply Round Up near hydrangeas (or other shrubs), it can make the leaves deform, look all wrinkled and even fall. Round Up does not need to be applied directly to the hydrangeas. Wind carries it to nearby shrubbery. Thus, whatever the lawn care service used may have had a similar effect on the hydrangeas. My shrubs usually go dormant in December; if yours do something similar too, it is possible that the chemicals used had this unintended effect on the hydrangeas.
Too much rain can make it hard for the roots to absorb oxygen too. The leaves may turn yellow and the plants could loose leaves. You would notice this if the soil was wet. For example, if you get some soil in between two fingers and press hard, you should see drops of water forming when the soil is too wet. Or when it has recently rained. Or when the sprinkler just went off.
Cercospora Leaf Spot is a fungal infection that many hydrangeas get. In rainy years, they can get heavy infestations that do not become visible until the Fall. Meaning the infestation is there but the green pigments in the leaves hide the lesions. The worst of these infected leaves can fall too (although I usually deadhead them myself). But it would be rare to defoliate so many shrubs without you noticing that the leaves are uuuuuuu-gly.
The plants that show signs of fungal infections should have their leaves deadheaded when the plants go dormant; throw them in the trash, not the compost pile. The same should be done with the spent blooms & plant debris when there are signs of fungal infections. Limit overhead waterings; instead, water the soil early in the mornings. Replace the mulch with new mulch if the infestation is severe. The are fungicides available to control (not to cure) leaf spot but they are expensive. But it is hard to justify the expense when the leaves are "soon" going to go dormant and brown out anyways.
The good news in all this is that you said you noticed that they are leafing out again! I only get new flowers with reblooming hydrangeas and -only in some years- with an unknown hydrangea that was already planted when I moved into the house.