Deprecation Warning - Current Server Discovery and Monitoring engine is deprecated

I’m seeing this warning only in production:

DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
(Use `node --trace-deprecation ...` to show where the warning was created)

I’m running Meteor 2.3.4. My understaning is that useUnifiedTopology was set to true by default in v2.2 Meteor Changelog | Meteor API Docs.

I also tried to set it in Meteor.settings:

 "packages": {
    "mongo": {
      "options": {
        "useUnifiedTopology": true
      }
    }
  }

I’m building with this Dockerfile:

# The tag here should match the Meteor version of your app, per .meteor/release
FROM geoffreybooth/meteor-base:2.3.4

# Copy app package.json and package-lock.json into container
COPY ./package*.json $APP_SOURCE_FOLDER/

RUN bash $SCRIPTS_FOLDER/build-app-npm-dependencies.sh

# Copy app source into container
COPY . $APP_SOURCE_FOLDER/

RUN bash $SCRIPTS_FOLDER/build-meteor-bundle.sh


# Use the specific version of Node expected by your Meteor release, per https://docs.meteor.com/changelog.html
FROM node:14.17.4-alpine

ENV APP_BUNDLE_FOLDER /opt/bundle
ENV SCRIPTS_FOLDER /docker

# Install OS build dependencies, which we remove later after we’ve compiled native Node extensions
RUN apk --no-cache --virtual .node-gyp-compilation-dependencies add \
    g++ \
    make \
    python \
  # And runtime dependencies, which we keep
  && apk --no-cache add \
    bash \
    ca-certificates

# Copy in entrypoint
COPY --from=0 $SCRIPTS_FOLDER $SCRIPTS_FOLDER/

# Copy in app bundle
COPY --from=0 $APP_BUNDLE_FOLDER/bundle $APP_BUNDLE_FOLDER/bundle/

RUN bash $SCRIPTS_FOLDER/build-meteor-npm-dependencies.sh --build-from-source \
  && apk del .node-gyp-compilation-dependencies

# Start app
ENTRYPOINT ["/docker/entrypoint.sh"]

CMD ["node", "main.js"]

Any ideas on how to resolve?