Gitlab rules with variable assignment does not work

Question

The variable in the rules is not being substituted to "Debug" when the job is run. The pipeline job is following...

variables:
  OBJECTS_DIRECTORY: obj
  NUGET_PACKAGES_DIRECTORY: ".nuget"
  SOURCE_PATH: src/

build:
  image: mcr.microsoft.com/dotnet/sdk:6.0
  tags:
  - fms
  variables:
    DEPLOY_CONFIGURATION: "Release"
  script:
  - echo "Branch => $CI_COMMIT_REF_NAME"
  - echo "building with configuration => $DEPLOY_CONFIGURATION"
  - |
    for project in $(find . -type f -name "*.csproj"); do
      echo "Running build for $project"
      dotnet build --configuration $DEPLOY_CONFIGURATION
    done
  extends: ".dotnet-build"
  cache:
    key:
      files:
      - "$SOURCE_PATH$OBJECTS_DIRECTORY/project-assets.json"
      - "$SOURCE_PATH$OBJECTS_DIRECTORY/*.csproj.nuget.*"
      prefix: "$CI_COMMIT_REF_SLUG"
    paths:
    - "$SOURCE_PATH$OBJECTS_DIRECTORY/project-assets.json"
    - "$SOURCE_PATH$OBJECTS_DIRECTORY/*.csproj.nuget.*"
    - "$NUGET_PACKAGES_DIRECTORY"
    policy: pull-push
    unprotect: false
    untracked: false
  stage: build
  before_script:
  - dotnet restore --packages $NUGET_PACKAGES_DIRECTORY
  rules:
  - if: "$CI_COMMIT_REF_NAME =~ /^develop$|^feature\\/[0-9A-Za-z_-\\+\\.]+$/"
    variables:
      DEPLOY_CONFIGURATION: "Debug"

The branch is feature/pipeline and the jobs with "Release" not matter what. The Gitlab documentation says otherwise. I am using GitLab Enterprise Edition 15.11.6-ee. Here is the output when the job starts...

$ echo "Branch => $CI_COMMIT_REF_NAME"
Branch => feature/pipeline
$ echo "building with configuration => $DEPLOY_CONFIGURATION"
building with configuration => Release

I am testing locally with a Gitlab-runner

Runtime platform arch=amd64 os=darwin pid=85068 revision=85586bd1 version=16.0.2