diff --git a/src/v/kafka/server/group.cc b/src/v/kafka/server/group.cc
index d0fcd5cee0ac8..c4efb71050fd4 100644
--- a/src/v/kafka/server/group.cc
+++ b/src/v/kafka/server/group.cc
@@ -2393,7 +2393,7 @@ void add_offset_tombstone_record(
       .partition = tp.partition,
     };
     auto kv = serializer.to_kv(offset_metadata_kv{.key = std::move(key)});
-    builder.add_raw_kv(reflection::to_iobuf(std::move(kv.key)), std::nullopt);
+    builder.add_raw_kv(std::move(kv.key), std::nullopt);
 }
 
 void add_group_tombstone_record(
@@ -2404,7 +2404,7 @@ void add_group_tombstone_record(
       .group_id = group,
     };
     auto kv = serializer.to_kv(group_metadata_kv{.key = std::move(key)});
-    builder.add_raw_kv(reflection::to_iobuf(std::move(kv.key)), std::nullopt);
+    builder.add_raw_kv(std::move(kv.key), std::nullopt);
 }
 } // namespace