Staszek Unfortunately, at this time, there is no way to change the log level for the onvif_autodiscovery daemon. However you can turn off the onvif_autodiscovery daemon once you have registered your cameras, as it does not serve a purpose beyond getting the camera registered in orchid. If you get new cameras you can turn the service back on temporarily to discover the new cameras.
To turn off:
sudo systemctl stop orchid_onvif_autodiscovery.service
To turn on:
sudo systemctl start orchid_onvif_autodiscovery.service
Let me know if you have any more questions.