terraform-version is also populated asynchronously.

website/docs/cloud-docs/api-docs/state-versions.mdx

@@ -52,7 +52,7 @@ Attribute | Description
 `resources-processed` | A Boolean flag indicating whether Terraform Cloud has finished asynchronously extracting outputs, resources, and other information about this state data.
 `serial` | The serial number of this state instance, which increases every time Terraform creates new state in the workspace.
 `state-version` | The version of the internal state format used for this state. Different Terraform versions read and write different format versions, but it only changes infrequently.
-`terraform-version` | The Terraform version that created this state.
+`terraform-version` | The Terraform version that created this state. Populated asynchronously.
 `vcs-commit-sha` | The SHA of the configuration commit used in the Terraform run that produced this state. Only present if the workspace is connected to a VCS repository.
 `vcs-commit-url` | A link to the configuration commit used in the Terraform run that produced this state. Only present if the workspace is connected to a VCS repository.