Hi, while chatting to the support, i also asked about the little fan there, and they said:
The extruder cooling fan is primarily activated when printing with materials like ABS that require cavity heating. This is essential to manage the temperature of the extruder and ensure proper filament flow during printing While the fan may not be necessary for lower-temperature materials like PLA or PETG, it can still operate to help with cooling if needed, especially during longer prints or when printing with complex geometries that may trap heat.
So i wouldn’t worry, i also have never seen it ON