I am also getting this notification. Although I am already using the suggested command. Is it giving the notification because I also have the site as a saved profile?
You can get the warning, if your stored site name is exactly the same as session URL. In that case WinSCP will actually use the stored site. You can use
/ini=nul
to isolate your script from your global configuration.
See https://winscp.net/eng/docs/scripting#configuration