Good Morning,
Looks like leaf scorch.  Leaf scorch on hydrangea is a common physiological problem. Typical symptoms include yellowing leaves, or irregular dry, brown blotches. Leaf tips and margins may turn brown, as well. Severely damaged leaves may drop from the plant. Leaf scorch results when the leaves lose water faster than it can be supplied by the roots, so wilting may occur before scorch is noticed. Common causes include inadequate watering, exposure to strong light (sunlight or reflected light), high temperatures, or dry, windy conditions. Scorch can also occur as a result of damaged roots or stems, such as from an injury, compacted soils, or overwatering or overfertilization.


Hydrangea: Leaf scorch | Hortsense | Washington State University (wsu.edu)


Another possibility could be aphids.  Look at the bottom of the distorted leaves for aphids. Their feeding can distort the leaves, too. Aphids can be controlled by spraying both sides of leaves with insecticidal soap (a garden product, not dish soap) or a few other garden products. Here is detailed info on aphids- https://www.extension.umn.edu/garden/insects/find/aphids-on-deciduous-trees-and-shrubs/

I hope this helps.  Thanks for using our service.

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