Command in dockerfile doesn't take effect

Below is my dockerfile. After the dependencies are installed, I want to delete a specific binary (ffmpeg) from the node_modules folder on the container, and then reinstall it using the install.js file that exists under the same folder in node_modules.

FROM node:16-alpine

WORKDIR /web

COPY package.json package-lock.json ./

ARG NODE_ENV
ENV NODE_ENV ${NODE_ENV:-development}

ARG _ENV
ENV _ENV ${_ENV:-dev}

RUN npm install

RUN rm /web/node_modules/ffmpeg-static/ffmpeg
RUN node /web/node_modules/ffmpeg-static/install.js

COPY . .

EXPOSE 8081
ENTRYPOINT [ "npm" ]

I want the rm and node commands to take effect on the container after the startup and when all the dependencies are installed and copied to the container, but it doesn’t happen. I feel like the commands after RUN are only executed during the build process, not after the container starts up.

After the container is up, when I ssh to it and execute the two commands above directly (RUN rm... and RUN node...), my changes are taking effect and everything works perfectly. I basically want these commands to automatically run after the container is up and running.

The docker-compose.yaml file looks like this:

version: '3'
services:
  serverless:
    build: web
    user: root
    ports:
      - '8081:8081'

    env_file:
      - env/web.env
    environment:
      - _ENV=dev
    command:
      - run
      - start
    volumes:
      - './web:/web'
      - './env/mount:/secrets/'