🐛 [#3688] Properly access the 'formio-like' data

Accessing dotted-keys like foo.bar in the underlying data
structure used by FormioData does not work, the point of
FormioData is to abstract this access.

src/openforms/registrations/contrib/objects_api/submission_registration.py

@@ -400,12 +400,7 @@ def get_object_data(
             }
         )
 
-        variables_values = FormioData(
-            {
-                **dynamic_values,
-                **static_values,
-            }
-        ).data
+        variables_values = FormioData({**dynamic_values, **static_values})
 
         variables_mapping = options["variables_mapping"]
         record_data: dict[str, JSONValue] = {}