Include doesn't support anchor scripts

Gitlab CI doesn't play well with script overriding and includes

include: 
  - local: '.gitlab/ci/frontend.yml'

Client Tests:
  extends: .g-frontend-lint-test
  variables:
    CACHE_COMPRESSION_LEVEL: "fast"
  script:
    - *yarn-lint-script
    - *yarn-test-script
  stage: test
  needs: ["Client Install Deps"]

You can’t use YAML anchors across different YAML files sourced by include. You can only refer to anchors in the same file. To reuse configuration from different YAML files, use !reference tags or the extends keyword.

This makes sense since include is a gitlab CI syntax and anchor are yaml syntax. So including a CI file does not imply the inclusion of all the yaml syntax.

I suggest you try to use the !reference or the extends keywords.