Question, while providing include_fields which does not include field registration I still get in the response for example

Are the registration fields optional?

Hmm, could you try this in v28.0.rc36 to see if you can still replicate the issue? If you can, could you share a minimal set of curl commands like this that replicates the issue: https://gist.github.com/jasonbosco/7c3432713216c378472f13e72246f46b