The Railway platform is deprecating its auto-injection of plugin variables in favor of explicit Database Reference Variables, which enable multiple databases to co-exist in a project, restrict database credentials to services that need them, and provide other benefits such as improved security and easier configuration. The change replaces implicit auto-injection behavior with explicit references that can be added from the Variables page in Service Settings, and has already backfilled existing services so no migration steps are required. With Database Reference Variables, users can now define database variables at the project environment level, reference them using a templated value, and enjoy features such as dynamic references, restricted credential sharing, and automatic re-deploys when reference variables are added or removed.