This is unavoidable, there is a loss of AC and DC power in the conversion, the general charger uses a switching power supply with higher efficiency, but is limited by the volume, so there is basically no PFC circuit, so the power factor is less than 0.7, and the rest of the energy is basically converted into heat. It is normal for the charger to be a little hot when charging, as long as there is no odor, it is not necessary to care about it, but it is best to put it in a ventilated place, because the heat will accelerate the aging of electronic components.