(Responding in part to @chadnewbry, and for any users who might be on Render.)

If this is an issue with env vars:

• First, you really don't want to commit your .env.production file to Git! This piece explains why: https://withblue.ink/2021/05/07/storing-secrets-and-passwords-in-git-is-bad.html
• On Render, you can set env vars through the Dashboard. This will work for Next.JS or any other web app/framework. More details here: https://docs.render.com/configure-environment-variables