fix balances query n+1

app/graphql/sources/active_record.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module Sources
+  class ActiveRecord < GraphQL::Dataloader::Source
+    # rubocop:disable Lint/MissingSuper
+    def initialize(model_class)
+      @model_class = model_class
+    end
+
+    def fetch(ids)
+      @model_class
+        .where(id: ids)
+        .index_by(&:id)
+        .slice(*ids)
+        .values
+    end
+  end
+end