Where does the package @netlify/serverless-functions-api come from?

While researching how Netlify functions get a Web API-flavored Request from regular node.js lambda HTTP requests, I encountered the package @netlify/serverless-functions-api.

The NPM entry has a link to GitHub, but the project is 404. The license file says it is MIT-licensed. Did this get rolled into a monorepo somewhere? Is it open source?

It’s a private repo. But you should be able to see the build output from NPM itself: @netlify/serverless-functions-api - npm (npmjs.com)