White discoloration of the nails or leukonychia can be due to many causes. Here are some of them. https://pmc.ncbi.nlm.nih.gov/articles/PMC8809498/ | Dr. Farrah

White spots on toe nails or finger nails are generally seen in children. We mistake it for calcium deficiency or any other vitamin deficiencies, but that is not the case. It’s generally idiopathic, that is without any cause as such, but in adults if you notice the discoloration, you notice the thinning or the thickening of the nails with white discoloration. It could commonly be a fungal infection. In case of any trauma, you might notice a little discoloration, plus if there is any growth under