Unless explicitly defined in the POST body, the OAuth2 Dynamic Client Registration flow defaults to response_types=code regardless of the grant_types parameter specified. This in turn results in the need to specify a never used redirect_uri parameter.
Flows which do not support redirection such as client_credentials and Resource Owner Password Grant should not require response_types to be specified and instead should default to "response_types":  (i.e. a blank value) and thus not require the redirect_uri parameter to be specified.
Currently unless response_types is explicitly defined in the POST body with "response_types": , regardless of the grant_types specified, a redirect_uri is required, which is breaking change client side registration APIs upgrading to AM 6.5.x.
Example working request:
Example broken request: