on the one hand, I was wrong, and as you said, I have confirmed that those specific merchants have not accepted the ‘read_shipping’ permissions.
On the other hand, my confusion has been generated by the fact that this ‘read_shipping’ permission is not required for the ‘/shipping_zones.json’ REST API endpoint (which is the equivalent to the GraphQL ‘deliveryProfiles’ query according to ShippingZone - REST).
With this, my question now is: is the requirement of this permission necessary? It highly complicates the REST to GraphQL API migration.