You don’t need to turn on/off Xiaomi power banks manually. When the power bank is connected to a device with a charging cable, it will start charging automatically without manual intervention.
The built-in button is only for checking the battery level and does not serve as a power switch. If no device is connected, the power bank's charging port will not output power. So you don’t need to worry about the power consumption.
The power bank will enter sleep mode automatically and turn off after about 25 seconds without any connected devices, with the indicator ceasing to flash.
Note:
Xiaomi power banks will not stop charging automatically after fully charging a phone. Xiaomi power banks will charge intelligently based on the phone's requirements, following the phone's charging logic.