diff --git a/api/registrations/serializers.py b/api/registrations/serializers.py
index dc4795dc132..99991356be6 100644
--- a/api/registrations/serializers.py
+++ b/api/registrations/serializers.py
@@ -394,6 +394,8 @@ def anonymize_registered_meta(self, obj):
                 for question in page['questions']:
                     if question['title'] in ANONYMIZED_TITLES and meta_values.get(question.get('qid')):
                         del meta_values[question['qid']]
+
+        strip_registered_meta_comments(meta_values)
         return meta_values
 
     def check_admin_perms(self, registration, user, validated_data):
@@ -619,3 +621,33 @@ class RegistrationStorageProviderSerializer(NodeStorageProviderSerializer):
         kind='folder',
         never_embed=True,
     )
+
+def strip_registered_meta_comments(messy_dict_or_list):
+    """Removes Prereg Challenge comments from a given `registered_meta` dict.
+
+    Nothing that uses APIv2 needs these comments:
+    ```
+    {
+        "registered_meta": {
+            "q20": {
+                "comments": [ ... ], <~~~ THIS
+                "value": "foo",
+                "extra": []
+            },
+        }
+    }
+    ```
+    """
+    if isinstance(messy_dict_or_list, list):
+        for obj in messy_dict_or_list:
+            strip_registered_meta_comments(obj)
+    elif isinstance(messy_dict_or_list, dict):
+        comments = messy_dict_or_list.get('comments', None)
+
+        # some schemas have a question named "comments" -- those will have a dict value
+        if isinstance(comments, list):
+            del messy_dict_or_list['comments']
+
+        # dig into the deeply nested structure
+        for nested_obj in messy_dict_or_list.values():
+            strip_registered_meta_comments(nested_obj)