Limited legacy subscriber webhook payload to v2 only (#11139)

no issue

- In v3 we don't need to support any legacy webhook formats
- Added a comment about the removal of the format when v2 is dropped

core/server/services/webhooks/serialize.js

@@ -70,14 +70,17 @@ module.exports = (event, model) => {
                 }
             };
 
-            // @TODO: remove in v3
-            // @NOTE: Our webhook format has changed, we still have to support the old format for subscribers events
-            if ('subscriber.added' === event) {
-                payload[docName] = [current];
-            }
+            // @NOTE: Our webhook format has changed, we still have to support the old format
+            //        for subscribers events. No need to support it passed v2 version
+            // @TODO: Remove whole if block when dropping Ghost v2
+            if (apiVersion === 'v2') {
+                if ('subscriber.added' === event) {
+                    payload[docName] = [current];
+                }
 
-            if ('subscriber.deleted' === event) {
-                payload[docName] = [previous];
+                if ('subscriber.deleted' === event) {
+                    payload[docName] = [previous];
+                }
             }
 
             return payload;