The;
sensor_t* sensor = esp_camera_sensor_get();
sensor->set_reg(sensor, 0x3008, 0x40, true ? 0x40 : 0x00);
Does enable standby on an OV3660, the current consumption of the board drops from about 135mA to 50mA when the standby command is issued.
However, if you then attempt to cancel standby mode the camera appears to stop working, all I get is images which are a pink screen.
And re-initialising the camera results in an error; 'Camera probe failed with error 0x103.
It would be really good if you could just light sleep the ESP32S3 so that the sketch can just pause rather than do complete restart as with deep sleep, with an OV3660 fitted the current used then drops to 4.7mA in light sleep.