Since RESTCONF didn’t exist in 6.2, I am assuming this is REST, but correct me if I am wrong.
I ran the action defined in examples.confd/rest/basic and used a JSON payload. I can see that there is a difference on “output”, that in 6.5 the module name is added. This may have been influenced when the support for RESTCONF was added. If you look at RFC 8040, section 3.6.2, you can see that the way it is done in 6.5 follows the RESTCONF standard. Most likely the REST interface was brought in line with RESTCONF.
If you would like to pursue this further, then you would need to open a ticket to see if it can be changed.