X-Forwarded-Host

No breaking changes are intended there either.

However, we base our implementation entirely on the AWS lambda implementation and API and so are limited by what they (continue to) support. Here’s an example of a “well that’s gone suddenly” that we had to react to recently, though it is not really adjacent to the functionality you are talking about:

https://answers.netlify.com/t/common-issue-tips-for-upgrading-your-netlify-functions-from-node-js-v8-10/6132