User in docker can't create folders and files - ruby

Question

I have a problem with creating folders and files within a docker container. I have a Ruby and Hanami web app deployed using Dockerfile and docker-compose yaml. Here is the content of both files for reference.
Dockerfile:
FROM ruby:2.7.5-bullseye
RUN apt-get update && apt-get install vim -y
RUN bundle config --global frozen 1
RUN adduser --disabled-login app_owner
USER app_owner
WORKDIR /usr/src/app
COPY --chown=app_owner Gemfile Gemfile.lock ./
COPY --chown=app_owner . ./
RUN gem install bundler:1.17.3
RUN bundle install
ENV HANAMI_HOST=0.0.0.0
ENV HANAMI_ENV=production
EXPOSE 2300
docker-compose.yml:
version: '3'
services:
postgres:
image: postgres
restart: unless-stopped
environment:
- POSTGRES_USER=${POSTGRES_USER}
- POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
- POSTGRES_DB=${POSTGRES_DB}
ports:
- 5432
volumes:
- postgres_staging:/var/lib/postgresql/data
web:
build: .
restart: unless-stopped
command: >
bash -c "bundle exec hanami db migrate
&& bundle exec rake initial_settings:add_default_language
&& bundle exec rake initial_settings:add_session_validity
&& bundle exec rake import_user:create
&& bundle exec rake super_admin:create
&& bundle exec rake create_parser_rules:start
&& bundle exec hanami assets precompile
&& cp -r apps/myapp/assets/webfonts public/webfonts
&& cp -r apps/myapp/assets/webfonts public/assets/webfonts
&& cp -r apps/myapp/assets/images/sort*.png public/assets
&& cp -r apps/myapp/assets/images/sort*.png public
&& cp -r apps/myapp/assets/images/ui-icons*.png public/assets/wordrocket
&& mkdir public/assets/images
&& cp -r apps/myapp/assets/images/sort*.png public/assets/images
&& bundle exec hanami server"
volumes:
- ./hanami_log:/usr/src/app/hanami_log
links:
- postgres
depends_on:
- postgres
nginx:
image: nginx:alpine
restart: unless-stopped
tty: true
ports:
- "${NGINX_PORT}:80"
volumes:
- ./nginx.conf:/etc/nginx/nginx.conf
depends_on:
- web
volumes:
postgres_staging:
web:
nginx:
The docker-compose has some initial commands that need to be run and the ones creating folders and files are failing. For example bundle exec hanami assets precompile fails with: Permission denied # dir_s_mkdir - /usr/src/app/public
The command created the folder and then copies over some files. I've confirmed this error by omitting the command from docker-compose and then tried running the command manually in the running container. I get the same error.
Is my configuration incorrect?
EDIT: Forgot one important thing: the problem occurs on the client's server running Ubuntu 20.04, while it works without issues on my dev laptop.
Thank you.
Seba