It is the way how a Lithium battery behaves while charging, that is why it is called CC/CV

When the battery is empty it has a lower voltage than the charging voltage, basically connecting 2 different levels of voltages together it is a shortcut. Then the Constant Current will step in.
When the battery is on voltage with the charging voltage the current will slowly drop further but the Constant Voltage will stat on its value..

Because the balancing current is much lower than the charging current then at the end of charging when the charging current has become very low the working of the balancing current will take the overhand.