Plant ID and disease
This looks like a mountain laurel, Kalmia latifolia, with leaf spots on the foliage. Mountain laurel are very susceptible to several leaf spots diseases and are not easy to grow. https://extension.umd.edu/hgic/topics/fungal-leaf-spots-shrubs
You did not mention how old the plant is and what site conditions they are located in. This plant requires an acid, cool moist, well drained soil in full sun to partial shade but grows best in the shade. When stressed due to environmental or cultural issues such as drought, poor soils, poor drainage, etc. they can be susceptible to insect or disease problems.
Many leaf spot diseases can be tough on the plants but does not kill them. The yellow leaves will fall off. Remove any affected foliage from the ground to prevent any overwintering spores. Make sure mulch is no thicker than two inches in depth and keep away from the stems. Water deeply during dry periods if possible. No chemical controls are recommended. If the shrub is not located in the best growing conditions, you can transplant to a partial shade location in a well drained soil. In general you can expect to see about 6 inches of new growth from a healthy plant.