How to add new non-dev environment

When i add another environment (let’s say “testing”), it’s being treated the same as development. This means, require-dev dependencies are installed, and an error occurs, saying vendor/bin/phpcbf: Permission denied.

I assume, the environments are classified by their name (production => production, staging => staging, everything else => development)

How can i “flag” an additional environment as “production-like”?