Stuck CIAM/External ID tenant with provisioningState "Failed": can't add admins, can't delete, sign-in returns AADSTS500208

We have a Microsoft Entra CIAM directory (External ID tenant) whose resource JSON shows "provisioningState": "Failed". Because of this, we can't add admins to the tenant itself, the tenant doesn't appear under Entra ID → Manage tenants (even for the Global Administrator), and the normal deletion flow requires being able to see it there.

Is there a way to force-delete a CIAM tenant that's stuck in a failed provisioning state?