I'd been watching a lot of YouTube videos about plants developing "brown" spots specially at the tip of the leaves and many people said it could be the "tap" water. Some municipalities in big cities add chlorine and fluoride to the water to keep it safe to drink but that is not good for plants. They recommend filtered water or at least you let the water the night before so the chlorine can evaporate. Do you fertilize your plant?. They needs nutrients that might not be present in the soil or the water you are providing, a good "organic" common indoor plant food every other or every three month should be ok. Just bought me one fiddle leaf fig and hopefully will do good. Good luck.