Which App Store Connect API should submit an Apple-hosted asset pack for external TestFlight review?

Hello,

Apple’s documentation appears inconsistent about which App Store Connect API should be used to submit an Apple-hosted Background Asset version for external TestFlight review:

• In WWDC25 “Discover Apple-Hosted Background Assets”, Apple says that the asset pack version can be submitted using the POST /v1/betaBackgroundAssetReviewSubmissions.
• In Uploading and versioning Apple hosted background assets, the external beta review instructions link to “Submit an app for beta review,” which uses POST /v1/betaAppReviewSubmissions.

These two resources have different behavior.

betaBackgroundAssetReviewSubmissions

I called the public API with the same resource structure used by the App Store Connect web UI:

POST https://api.appstoreconnect.apple.com/v1/betaBackgroundAssetReviewSubmissions

{
  "data": {
    "type": "betaBackgroundAssetReviewSubmissions",
    "relationships": {
      "backgroundAssetVersion": {
        "data": {
          "type": "backgroundAssetVersions",
          "id": "<BACKGROUND_ASSET_VERSION_ID>"
        }
      }
    }
  }
}

The public API returned 404 PATH_ERROR:

The resource 'v1/betaBackgroundAssetReviewSubmissions' does not exist.

However, the App Store Connect web UI uses the private endpoint below with the same payload and receives HTTP 201:

POST https://appstoreconnect.apple.com/iris/v1/betaBackgroundAssetReviewSubmissions

The public endpoint is also absent from the current App Store Connect OpenAPI specification.

betaAppReviewSubmissions

I also tested the public POST /v1/betaAppReviewSubmissions endpoint.

When I supplied a backgroundAssetVersion relationship, the API returned 409:

'backgroundAssetVersion' is not a relationship on the resource
'betaAppReviewSubmissions'.

You must provide a value for the relationship 'build'.

The build relationship only accepts the builds resource type, not backgroundAssetVersions. Therefore, betaAppReviewSubmissions can submit an app build but cannot submit a Background Asset version.

Could Apple please clarify:

1. Which public API should be used to submit a Background Asset version for external TestFlight review?
2. Is betaBackgroundAssetReviewSubmissions intended to be exposed through the public App Store Connect API?
3. Is the link to betaAppReviewSubmissions in the Background Assets documentation incorrect?
4. When will the public documentation and OpenAPI specification be updated?

Thank you.