Internal server error when using CiConf GraphQL query with include:project

Context

On gitlab.com, since a few days, I experience a lot of Internal server error issues when I use the GraphQL query CiConf. This seems to appear when using one or more include:project. But I didn't find any clue about what exactly triggers it

Example of query:

• Query

  query getCiConfig($projectPath: ID!, $content: String!) {
    ciConfig(projectPath: $projectPath, content: $content) {
      mergedYaml
      errors
      warnings
      status   
      includes {
        location
        type
        extra
        contextProject
      }
      stages {
        nodes {
          name
          groups {
            nodes {
              name
              size
              jobs {
                nodes {
                  name
                  script
                }
              }
            }
          }
        }
      }
    }
  }

• Variables

  {
    "content": "include:\n  - project: 'bigtech-b-thomas/templates/ci'\n    ref: '1.0.2'\n    file: 'templates/go/go.yml'\n\nstages:\n  - build\n\nharcoded_job:\n  stage: build\n  script:\n    - echo ok\n\n",
    "projectPath": "bigtech-b-thomas/frontend/landing-page"
  }