Cats chewing themselves is a normal behavior, sometimes to clean their fur, sometimes to practice hunting skills, or to express their emotions. Cats learn how to trim their claws and clean their fur when they are young, which is done by biting their claws. This is also part of cats' hunting skills, as they practice catching prey by biting their own necks or tails.
If your cat often bites itself, you can try providing them with some cleaning toys, such as cat pounding pills or cat Comb so they can do these things without biting themselves. You can also provide them with toys, such as toys that swing regularly or rolling toys, to help them practice their hunting skills. If your cat bites itself frequently or painfully, you should consult a veterinarian to rule out possible health issues.
