Configuration by environment falsy states the hostname is used, while it is the domain

[inktrap]

For the original issue see getgrav/grav/issues/1781. In a nutshell:

In the docs it is stated that configuration by environment works by hostname, while in fact it works by parts of the domain (e.g. example.com) which includes domain names such as e localhost. A valid hostname is also a valid domain name, but a valid domain name may not necessarily be valid as a hostname.

Secondly, please consider adding a note similar to the following:

If your grav installation can be reached by different domains, you have to create (or symlink) a separate folder for each domain. If such a folder or symlink is not present, the default configuration will be used, which might not be in your interest.

(And, clarification, this is not based on the protocol).

[OleVik]

You can edit the page directly on GitHub and submit a Pull Request.