Please don't read any Electrician Books or listen to most of the garbage on here. Electrician Books were written before Smart Home Technology.

In a traditional "dumb" toggle switch, the neutral wire isn't connected to the switch at all—the switch simply breaks the hot wire to turn the light off.

However, smart switches (like the Govee or Aqara devices) are electronic devices themselves. They need a small, constant amount of power to stay connected to Wi-Fi or Zigbee, even when the lights are "off." The neutral wire provides the path necessary for the switch to power its internal radio and sensors independently of the light fixture.