First, the meat is not fine enough and not sticky enough.
Second, add some egg white, put some starch in the right amount, but not too much, otherwise the taste of meatballs will feel stiff and dead.
Third, when the meatballs are placed in the pot, the temperature of the water is kept at 40 C-50 C. After the meatballs are finished, slowly boil them with low fire and take them out when they are cooked. (If the temperature is too high, the meatballs will be unevenly heated, and some will be overcooked, and the meatballs will be broken under boiling water.)