A hard scab on the bridge of the cat's nose may be cat moss or other skin diseases, or it may be that the cat was accidentally injured. It is best to check whether there are scabs elsewhere on the cat's body. If so, it should be on the skin. The disease needs treatment. If not, the wound should be broken and scabbed, and it will recover in a few days. Pay attention to keeping the cat clean and deworming regularly. If it has a skin disease, the cat needs to be isolated from other healthy cats.