replicated application behind traefik proxy

docker-compose.yml

services:
  proxy:
    image: traefik:v2.8
    ports:
      - 18880:80
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
    command:
      - --providers.docker
      - --entryPoints.web80.address=:80

  app:
    image: my-applicaltion
    restart: always
    deploy:
      replicas: 3
      mode: replicated
    labels:
       - traefik.http.routers.who.rule=PathPrefix(`/`)