How to identify the user is single space guest user from REST API

Hi there,

We are testing out single space guest users with our apps on Confluence Cloud. Based on the document, the Get current user REST API will return isExternalCollaborator to identify the user is an external collaborator user.

However, when I log in as the guest user to access the invited single space, the API return ‘isExternalCollaborator’: false.

May I know is there any other way to identify guest users?