Why does the Xiaomi Smart Air Fryer 5.5L make some noise when used?

The Xiaomi Smart Air Fryer 5.5L will have an abnormal sound when used. The sound source is mainly generated by hot air circulation. This is a normal phenomenon, so please feel free to use it.
Note:
The noise of the Xiaomi Smart Air Fryer 5.5L is about 50-60dB (A) when in use.