A note on BMS operation:
All BMSs of any kind can do is to shut power off completely when a limit is exceeded. They cannot modulate power (that's what your controller is there for, and to do that job it requires the controller's complexity and hardware, or that of an SMPS / DC-DC converter capable of the full worst-case power level of the entire system)
So if your system is shutting completely off, no power, whenever you exceed 20A, then that's your BMS protecting the battery and itself.
But if your system never shuts off at 20A, just never exceeds that amount of current regardless of load on the motor, it's not the battery or BMS doing it, it's all in the controller/display system. Nothing you change in the BMS will affect this.