Traefik gets invalid IP

docker-compose.yml

version: "3.8"

services:

  traefik:
    image: "traefik:v2.3"
    command:
      - --log.level=DEBUG
      - --api.insecure=true
      - --api.dashboard=true
      - --api.debug=true
      - --providers.docker=true
      - --providers.docker.exposedbydefault=false
      - --entrypoints.web.address=:80
      - --providers.docker.network=web
    ports:
      - "80:80"
      - "8080:8080"
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock:ro"
    networks:
      - web

  whoami:
    image: "traefik/whoami"
    labels:
      - traefik.enable=true
      - traefik.http.routers.whoami.rule=Host(`whoami.localhost`)
      - traefik.http.routers.whoami.entrypoints=web
      - traefik.docker.network=web
    networks:
      - web
      - backend

networks:
  web:
  backend: