next.config.js needed the following:

    module.exports = {
    ...
    env: {
        AUTH0_SECRET: process.env.AUTH0_SECRET,
        APP_BASE_URL: process.env.APP_BASE_URL,
        AUTH0_DOMAIN: process.env.AUTH0_DOMAIN,
        AUTH0_CLIENT_SECRET: process.env.AUTH0_CLIENT_SECRET,
        AUTH0_CLIENT_ID: process.env.AUTH0_CLIENT_ID,
        NEXT_PUBLIC_COGNITO_IDENTITY_POOL_ID:
            process.env.NEXT_PUBLIC_COGNITO_IDENTITY_POOL_ID,
    },
};