The vehicle 5V3.4A is not fast Charge, because fast charge usually refers to the charger or device that supports the fast charging protocol, such as Qualcomm's Quick Charge or Huawei's SuperCharge, which can fully charge the device in a short time.
5V3.4A only indicates the voltage and current output of the charger, where 5V indicates voltage and 3.4A indicates current, and it does not have a clear fast charge protocol support, so it cannot be called fast charge. To achieve fast charging, you need to use chargers and devices that comply with the corresponding fast charging protocol.