There are many reasons why a cat may bite, some common reasons may include:
Stress response: Cats may bite to protect themselves when they feel threatened.
Playing: Cats may play with people as toys, especially young cats.
Pain: If your cat is in pain or discomfort, he may bite to express his distress.
Dissatisfaction: A cat may bite because it is dissatisfied. For example, it does not like being lifted or touched somewhere.
Response to stress: Cats may bite due to excessive stress.
If your cat bites you suddenly, it is best to contact your veterinarian as soon as possible to check your cat's health to make sure it does not have any medical problems. At the same time, you can also consider seeking the help of a professional behavioral counselor to understand the reasons why your cat bites and solve the problem.