Next.js should unconditionally use NODE_ENV=development and NODE_ENV=production for next dev and next build respectively in the following areas:

• .env.* loading
• Client-side bundle inlining
• Server-render time
• next/babel plugin internal mode (fix(next/babel): read env from caller, not process #20679)
• Webpack mode (fix(next/babel): read env from caller, not process #20679)

The only way to read a "misconfigured" NODE_ENV (e.g. NODE_ENV=staging) should be in next.config.js. This is only allowed for backwards compatibility.

I believe we also have to allow it to override what Babel "env" is loaded. I don't feel strongly about this.

Next 11 should disallow all non-standard values for this and immediately exit. This behavior should be implemented by whatever PR closes this behind a future flag.

We also need to fix this message:

warn  - You are using a non-standard "NODE_ENV" value in your environment. This creates inconsistencies in the project and is strongly advised against. Read more: https://err.sh/next.js/non-standard-node-env