Browning leaves indicate fungal infection or winter kill in most cases. Closely look at whether the browning starts with spots that enlarge and spread or the leaf overall turning brown in a uniform manner. If it is from winter kill, the leaves will fall and new ones emerge. https://www.gardeningknowhow.com/ornamental/shrubs/holly/leaf-scorching-in-holly.htm.
If you find spots, you are facing disease.