This condition in cats may be caused by a variety of reasons. Here are some possible causes and suggestions:

Disease or infection: The cat may be infected with a disease, such as influenza, feline infectious peritonitis, etc. These diseases may cause weakness in the limbs of the cat. It is recommended to take the cat to the veterinarian promptly for diagnosis and treatment.

Malnutrition or dehydration: Cats may not be getting enough nutrients or water, resulting in weakness. Make sure your cat has plenty of water and a proper diet.

Poisoning: Cats may accidentally eat toxic substances, such as pesticides, cleaning agents, etc. If you suspect your cat has been poisoned, contact your veterinarian or animal emergency center immediately.

Injury or pain: Your cat may have an injury, such as a broken bone, sprain, or other physical pain, which may cause it to be reluctant to move. Check the cat's body for any obvious wounds or abnormalities.

Stress or pressure: Cats may be experiencing stress or pressure, such as changes in the environment, the presence of strangers or other animals. Try to provide a quiet, comfortable environment for your cat.