Get real IP address behind GCP external LB

My WordPress instance is behind a Google Cloud External Load Balancer, because of which WordPress is detecting the wrong client IP (actually it is taking the Load Balancer IP as the client IP and blocking it). Directly using X-Forwarded-For will not be a good option due to the reasons given in the docs.
Please provide a way to deal with this situation if the server is Apache or Nginx or LiteSpeed.