Certified GKH Gardening Expert
Have you fertilized recently? If you have not, then it could be lacking in nutrients. Also, they don't like direct sunlight, so they could be getting too much light. Unfortunately, over and underwatering can cause this too. Can you include a photo, and a description of the care that you provide for it?
Here is an article for guidelines on how to care for these: https://www.gardeningknowhow.com/houseplants/peace-lily/peace-lily-plants.htm