Limelight Hydrangeas Leaf Drop - August 2021

Yesterday, I posted a couple of photos of the Prairie Winds Totem Pole Switch Grass that I planted in our front porch bed.  While I was over there taking those photos, I noticed that our Limelight Hydrangeas were in bad shape.  Ut oh.  These things have always been so very happy and have performed so very well in their spot.  But, this year, something is wrong.  Bad wrong.  

They have flowered (profusely), but when you look at them, you can see that they've dropped A LOT of leaves.  Here's a photo of the pair of them below.  Notice the curled, brown leaves on the ground. 

Here, below, is a closer look:

What is so hard to figure out is that the TIPS of the plant are seemingly happy and growing.  Below, shows some of the new growth:

I'm guessing that the Spring drought has given these some trouble and they're showing water-related stress, so I'm planning on soaking them both with the hose a couple of times this week to see if I can get them to recover in any meaningful way while the heat of August is beating down on them. 

These were some of the original plants that went in when we built our home and they've THRIVED where they were, but this sudden decline has me very worried about their future.