Our API includes a call to get a list of all spaces:

• https://developer.atlassian.com/cloud/confluence/rest/v2/api-group-space/#api-spaces-get

The description states:

Only spaces that the user has permission to view will be returned.

This suggestion is to allow all spaces to be returned, even those that the user running the call does not have permission to view.

Note that the same user can currently go to Confluence Settings > Space Permissions and view a list of all spaces here, including spaces that the user does not have access to. However, there is no export option available on this screen.