Li-ion cells really hate being left charging all the time. If the charger does not turn off the voltage to the cells, and lets them settle down to their resting voltage, then the cells can be damaged. The more often and longer they are forced to stay at the full charging voltage (because the charger never stopped) the worse the damage.
IMO if charging isn’t stopped automatically then they’re not using a charger, they’re just using a power supply and (maybe) hoping that the BMS stops the charge.