Why did my blue cat's fur turn white?
The whitening of a cat's fur could be due to malnutrition. Feeding a British Shorthair only dry cat food or a single type of food can lead to nutritional imbalances, which can hinder healthy fur growth. Inadequate grooming can also cause the fur to turn white. 
In daily life, when feeding your British Shorthair, choose a high-quality, nutritionally balanced cat food. Supplement with cooked fish, chicken, or beef, carefully controlling the salt and oil content. Meat should generally be given 3-5 times a week. Also, give small amounts of apple puree and carrots. After providing the basic nutrients your British Shorthair needs, you should supplement their diet with additional nutrients, such as adding lecithin supplements like those found in cat food. You can also give them an egg yolk once a week.
Regular grooming is essential for your British Shorthair. Improper bathing methods can damage its fur. Use a cat-specific shampoo like Taiqu when bathing your cat. After bathing, dry its fur thoroughly with a hairdryer. When brushing your British Shorthair, use a cat-specific comb to avoid damaging its fur.