VueJS files are hidden on Docker

Hi. I install NextCloud server on Docker. Here the Docker Compose file:

version: '3'

services:
  mysql:
    image: mysql:8.0
    restart: always
    ports:
      - "3306:3306"
    command: mysqld --default-authentication-plugin=mysql_native_password
    volumes:
      - /data/mysql:/var/lib/mysql
    environment:
      - MYSQL_ROOT_PASSWORD=root
      - MYSQL_DATABASE=app
      - MYSQL_USER=app
      - MYSQL_PASSWORD=secret
    networks:
      - app-network

  phpmyadmin:
    image: phpmyadmin/phpmyadmin
    environment:
      - PMA_ARBITRARY=0
      - PMA_HOST=mysql
      - PMA_PORT=3306
      - PMA_USER=app
      - PMA_PASSWORD=secret
    ports:
      - "81:80"
    volumes:
      - /sessions
    networks:
      - app-network
  
  app:
    image: nextcloud
    restart: always
    ports:
      - 8080:80
    volumes:
      - /data/nextcloud:/var/www/html
    environment:
      - MYSQL_PASSWORD=secret
      - MYSQL_DATABASE=app
      - MYSQL_USER=app
      - MYSQL_HOST=mysql
    networks:
      - app-network
    
networks:
  app-network:
    driver: bridge

But when I check the folder /data/nextcloud/core, there is no VueJS files. But in the GitHub version, it still has. GitHub - nextcloud/server: ☁️ Nextcloud server, a safe home for all your data