### Summary

Description:
I am encountering an issue with my Next.js application deployed on Heroku, specifically related to the callback URL for authentication. Here's a summary of the problem:

Issue
I have implemented authentication in my Next.js app using the next-auth library, and the login buttons are configured to use the correct callbackUrl as follows:

signIn('github', { callbackUrl: `${process.env.NEXT_PUBLIC_APP_URL}/api/auth/callback/github` })

In production, when users click the "Login with GitHub" button, they are redirected to a localhost URL instead of the Heroku app's URL.

Environment
- Next.js app using next-auth
- Deployed on Heroku
- Environment variables are correctly set, including NEXT_PUBLIC_APP_URL

Error Messages
- When users click the login button, they are redirected to http://localhost:PORT/api/auth/callback/github.
- The browser console shows the error: "crbug/1173575, non-JS module files deprecated."

Steps Taken
- Checked and verified that NEXT_PUBLIC_APP_URL environment variable is correctly set on Heroku.
- Restarted Heroku dynos.
- Added console.log statements for debugging, which showed the correct value of NEXT_PUBLIC_APP_URL.

Expected Behavior
When clicking the login button, users should be redirected to the Heroku app's URL for authentication (https://your-heroku-app.herokuapp.com/api/auth/callback/github), not localhost.