Env variables from .env* file don't expose to next.config.* anymore

[fliptheweb]

What version of Next.js are you using?

10.0.8

What version of Node.js are you using?

14.7.0

What browser are you using?

any

What operating system are you using?

macOS

How are you deploying your application?

local, codesandbox

Describe the Bug

Env variables don't expose to next.config.js and not available w/o manual using dotenv package.
Seems like after '10.0.8' nextjs starts to use next-env after next.config loaded.

Expected Behavior

We should be able to use Env variables in next.config, webpack, plugins configurations.

To Reproduce

Sandbox with 10.0.8 and the behavior:
https://codesandbox.io/s/nextjs-1008-process-env-bug-wmwkn
in terminal

check VAR env: undefined
check NEXT_PUBLIC_VAR env: undefined
warn  - Detected next.config.js, no exported configuration found.https://err.sh/vercel/next.js/empty-configuration
info  - Loaded env from /sandbox/.env

Sandbox with 10.0.7 w/o:
https://codesandbox.io/s/nextjs-1007-process-env-nvnnh
in terminal

Loaded env from /sandbox/.env
check VAR env: FOO
check NEXT_PUBLIC_VAR env: BAR

[matamatanot]

Check #22879.
You can try out https://github.com/vercel/next.js/releases/tag/v10.0.9-canary.2 .

[ijjk]

Closing as a duplicate of #22811 per above

[balazsorban44]

This issue has been automatically locked due to no recent activity. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.