The summer sun here is quite strong so I suggest making sure it gets shade starting around 11am (no afternoon sun). No evening sun either. Transplant it if it is getting more sun than that. My shrubs have handled 110+ temps in prior years with little leaf damage but they got zero afternoon/evening sun (only bright shade) and were already established by the time the 110s hit.

Also, since it is a new shrub planted in the summer, give it even more shade with a chair/umbrella/etc and give it more water than in the Spring. I give mine 1g in the Spring; 1.5-2g in the summer per watering. During the daily 100s, I water 3 times a week, provided a finger inserted to s depth of 4" fels dry. Add 2-3" of mulch year around past the drip line to further help the plant. And watch for leaves browning from the edges inwards, an indication that they need more water.

The round leaf spots can be ignored for now but are usually common issues due to overhead watering so, as a precaution, water the soil always, never the leaves. To remove ugly leaves, cut the petiole that connects the leaf to the stem.

Hydrangeas get stressed when planted after late May here so continue giving it TLC and check it often in its first few summers.

I have been looking for a TS/TTS locally. Where are you and where did you find yours?