fix: only add delta bytes when changing app data value

crates/app/src/routes/api/v1/app_data.rs

@@ -160,7 +160,14 @@ pub async fn update_value_request(
     }
 
     // ...
-    if let Err(e) = data.add_app_data_used(app.id, req.value.len() as i32).await {
+    // we only need to add the delta size (the next size - the old size)
+    if let Err(e) = data
+        .add_app_data_used(
+            app.id,
+            (req.value.len() as i32) - (app_data.value.len() as i32),
+        )
+        .await
+    {
         return Json(e.into());
     }