How to deploy an app that uses external sign-in provider using Docker?

I am trying to make an app available online using Docker, but I'm struggling with the Google sign-in part. This is an extract from the docker compose file I've been using:

version: '3'
services:
  nginx:
    image: customImage
    ports:
      - "80:80"
      - "443:443"
    ...

  api-service:
    image: customImage
    ...

In the nginx service I configured the proxy as follows:

location ^~ /api {
  proxy_pass http://api-service:7000;
}

When hitting the public domain the frontend loads OK. However, when trying to sign-in using Google I get the Invalid parameter value for redirect_uri: Non-public domains not allowed: http://api-service:7000/api/auth/google/redirect error message. How should I approach this and configure it in a way so it looks like the request is coming from the public domain. Thx in advance for your help.