Hi,

Yes, that would count against your bandwidth allowance. Any traffic that goes over the public interface is billed, regardless of the destination.

The documentation on bandwidth billing was recently updated to clarify that:

Any data transfer sent by a Droplet using a public network interface will count against the transfer pool for that Droplet’s account. All IPv6 traffic uses the public interface. Data transfer between Droplets over the private network uses a private network interface.