Speed accuracy analysis of servo motor acceleration and reduction gear

The servo motor is used with the reducer, such as the planetary reducer. The reducer has a reduction ratio. The servo motor outputs the specified speed. After the reducer decelerates and increases the torque, will the speed accuracy of the output shaft of the reducer be improved? Or does the reducer affect the speed accuracy of the servo motor? Is the speed accuracy of the output shaft of the reducer obtained by dividing the speed accuracy of the servo motor by the reduction ratio? Or does the reducer have no effect on the speed accuracy of the servo motor? Please consult everyone!