Unable to change php version of wordpress docker image

My wordpress container has php version 7.3 but my docker-compose file looks like this

    build:
      context: ./
      dockerfile: Dockerfile
    image: wordpress:php8.1-fpm
    volumes:
      - ./wordpress:/var/www/html

No metter what I do always is 7.3. Its strange that where I start docker compose up system pull two images

1. wordpress php7.3-fpm
2. wordpress php8.1-fpm

When I inspect my wordpress container it says that I am using php8.1-fpm but when I print php version inside of container php version is 7.3?

Thanks for helping me.