You'd better make pigeon soup with old pigeons. This is because the old pigeon has a low fat content, so the soup will not be so greasy, while the young pigeon has a high fat content, so the soup will be greasy.
The meat of old pigeons is old, and it will not rot if cooked for a long time, and the more it is cooked, the more fragrant it will be. The meat of squab is tender, and it will be soft and rotten when cooked for a while, which will affect the taste of soup.
The meat of the old pigeon is sweeter, and the more it is cooked, the sweeter the soup is. However, the meat quality of squab is not so sweet. If it is cooked for a long time, it will rot and it will not make a delicious thick soup.
The nutritional value of old pigeons is richer than that of young pigeons, and the soup made by old pigeons can cook more nutrients, and the soup made by old pigeons is more delicious.