The read:content-details:confluence scope is a granular one and the rollout of these new type of scopes has been paused a few days ago (see Pausing the rollout of new scopes for Forge and OAuth 2.0 (3LO) apps).
Please use the read:confluence-user, even if it’s marked as DEPRECATED in the documentation you shared while we work on updating the documentation to reflect the announcement.
Hope this helps,
Caterina