Hi @zhitch
This post explains more about bandwidth What does actually count in bandwidth? - #2 by luke as well as Billing → Bandwidth usage documentation which says:
Metered usage consists of all outgoing data traffic on your team’s sites, including:
- pages, files, assets, and other responses served to site visitors on production sites, branch deploys, or Deploy Previews.
- outgoing data sent by your sites in proxied API requests, including requests to Netlify Functions.
You might find the following support guide useful reading