What do you see in your plants that make you think the shrimp are eating them? Pictures? What type of shrimpp do you have?
Fresh water shrimp are in general all small and would have diffuculty getting the plant in there mouth. mainly shrimp eat algae, bacteria and dead material. I have never seen my shrimp eat any plants.
If the plants look damaged the most likely cause is a nutrient deficiency that is making it hard for your plants to grow.
Plants with low growth chemistry in the water, and perhaps even the wrong lighting, die back naturally. At first this may not be particularly noticeable to the human eye but shrimp will see it and eat the dead tissue.
Most shrimp will crawl over plants and pull bits of algae and other things off the leaves but don't normally damage the leaves. But if they are hungry, they will eat plants.