Error: getaddrinfo ENOTFOUND with docker-compose server definition

I'm building a react, Node App and I'm using docker-compose my docker compose definition looks like this:

version: "3"
services:
  frontend:
    stdin_open: true
    container_name: firestore_manager
    build:
      context: ./client/firestore-app
      dockerfile: DockerFile
    image: rasilvap/firestore_manager
    ports:
      - "3000:3000"
    volumes:
      - ./client/firestore-app:/app
    environment:
      - BACKEND_HOST=backend
      - BACKEND_PORT=8081
    depends_on:
      - backend
  backend:
    container_name: firestore_manager_server
    build:
      context: ./server
      dockerfile: Dockerfile
    image: rasilvap/firestore_manager_server
    ports:
      - "8081:8081"
    volumes:
      - ./server:/app
    environment:
      - BACKEND_HOST=backend
      - BACKEND_PORT=8081

I'm trying to access to the NodeJs backend endpoints using the backend prefix defined in the docker-compose file, but I'm getting an Error: getaddrinfo ENOTFOUND firestore_manager_server, the same is happening using the container name: firestore_manager_server.

As you can see in the next urls:

firestore_manager_server:8081/firestore?collection=test&field=nombre&value=xxxx
backend:8081/firestore?collection=test&field=nombre&value=xxxx

I don't have any problem using localhost.

The next is the result of the docker ps command:

Any ideas?