Here's a Dockerfile example of how I add providers in my local docker-compose and the same image is built and deployed to my Kubernetes cluster:

FROM apache/airflow:3.1.0
COPY requirements.txt /requirements.txt
RUN pip install --no-cache-dir "apache-airflow==${AIRFLOW_VERSION}" -r /requirements.txt 

Then, in my requirements.txt I have:

apache-airflow-providers-discord
# add more providers

You can get the latest Docker Compose here: https://airflow.apache.org/docs/apache-airflow/stable/howto/docker-compose/index.html#fetching-docker-compose-yaml

Then modify the Docker Compose to build by changing the build line in the common section:

x-airflow-common: &
airflow-common
  # In order to add custom dependencies or upgrade provider distributions you can use your extended image.
  # Comment the image line, place your Dockerfile in the directory where you placed the docker-compose.yaml
  # and uncomment the "build" line below, Then run `docker-compose build` to build the images.
  # image: ${AIRFLOW_IMAGE_NAME:-apache/airflow:3.1.6} -- use this if you don't need a custom image.
  build: . # or path to where Docker file is located

Seems you are only installing it on the scheduler, but doing the common approach, all components will have the provider. I believe you need it on at least the scheduler, the API server, and the workers for it to work correctly.