How to run the application on 80 port?

Question

I have a react app running on AWS as Docker container managed by Kubernetes. It also uses nginx, I'm not sure for what.
When I upload my local changes to GitLab repo, it every time deploys on 8000 port of my ec2 machine. I don't want that my app's url has :8000 in it, can anybody help me with it? What exactly affects on application's port?
Dockerfile

# build environment
FROM node:13.12.0-alpine as build
WORKDIR /app
ENV PATH /app/node_modules/.bin:$PATH
COPY package.json ./
COPY package-lock.json ./
#RUN npm install --legacy-peer-deps
RUN npm install
RUN npm install [email protected] -g
COPY . ./
RUN npm run build

# production environment
FROM nginx:stable-alpine
COPY --from=build /app/build /usr/share/nginx/html
COPY fullchain.crt /etc/ssl/fullchain.crt
COPY unpluggedapp.key.pem /etc/ssl/unpluggedapp.key.pem
COPY nginx.conf /etc/nginx/nginx.conf
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]

docker-compose

version: '3'
services:
  admin:
    image: registry.gitlab.com/......:<VERSION>
    environment:
      REACT_APP_URL: .......
    ports:
      - 80:80
      - 8443:443
    restart: on-failure

nginx.conf

user  nginx;
worker_processes  auto;

error_log  /var/log/nginx/errors.log notice;
pid        /var/run/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/accesses.log  main;

    sendfile        on;
    #tcp_nopush     on;

    keepalive_timeout  65;

    #gzip  on;


server {

  listen 80;
  listen [::]:80;
  server_name admin-dev.unpluggedsystems.app;
 #   return 301 http://$server_name$request_uri;

  root /usr/share/nginx/html;
  index index.html;
  
  location /api/7/apps/search {
   proxy_pass http://ws75.aptoide.com/api/7/apps/search;
   proxy_set_header X-Forwarded-For $remote_addr;

  }
location ~ \.(apk)$ {
  proxy_pass https://pool.apk.aptoide.com;
  proxy_set_header X-Forwarded-For $remote_addr;
}
}
}

.gitlab-ci.yml

stages:
  - build
  - deploy

services:
  - docker:stable-dind
variables:
  DOCKER_DRIVER: overlay2
  DOCKER_TLS_CERTDIR: ""
  REGISTRY_URL: registry.gitlab.com/......
  DOCKER_BUILD_ID: ${CI_COMMIT_SHORT_SHA}
  CONTAINER: ./container.txt

image: node:latest

Build image:
  stage: build
  tags:
    - runner
  image: docker:git
  services:
    - docker:stable-dind

  script:
    - docker login ${REGISTRY_URL} -u ${CI_REGISTRY_USER} -p ${CI_REGISTRY_PASSWORD}
    - docker build --network host -t ${REGISTRY_URL}:${DOCKER_BUILD_ID} .
    - docker push ${REGISTRY_URL}:${DOCKER_BUILD_ID}
  only:
    - dev
    - master

Deploy:
  stage: deploy
  tags:
    - runner
  before_script:
    - 'command -v ssh-agent || ( apt-get update -qy && apt-get install openssh-client -y )'
    - eval `ssh-agent -s`
    - mkdir -p ~/.ssh
    - chmod 700 ~/.ssh
    - echo "Lkey.pem" >> ~/.ssh/Lkey.pem
    - '[[ -f /.dockerenv ]] && echo -e "Host *\n\tStrictHostKeyChecking no\n\n" > ~/.ssh/config'
    - chmod 400 Lkey.pem
    - chmod 400 ~/.ssh/Lkey.pem
    - ssh -T -i "Lkey.pem" [email protected]
  script:
    - ssh -T -i "Lkey.pem" [email protected] "cd client; sed -E -i 's/(.*up_admin_client:).*/\1${DOCKER_BUILD_ID}/' docker-compose.yml ; docker-compose up -d"
  only:
    - dev