Fix NewPayload Validation during header download (#10837)

Cherry pick PR #10093 into the release branch

Co-authored-by: Minhyuk Kim <kimminhyuk1004@gmail.com>

turbo/engineapi/engine_server.go

@@ -768,7 +768,18 @@ func (e *EngineServer) HandleNewPayload(
 			if !success {
 				return &engine_types.PayloadStatus{Status: engine_types.SyncingStatus}, nil
 			}
-			return &engine_types.PayloadStatus{Status: engine_types.ValidStatus, LatestValidHash: &headerHash}, nil
+
+			status, _, latestValidHash, err := e.chainRW.ValidateChain(ctx, headerHash, headerNumber)
+			if err != nil {
+				return nil, err
+			}
+
+			if status == execution.ExecutionStatus_Busy || status == execution.ExecutionStatus_TooFarAway {
+				e.logger.Debug(fmt.Sprintf("[%s] New payload: Client is still syncing", logPrefix))
+				return &engine_types.PayloadStatus{Status: engine_types.SyncingStatus}, nil
+			} else {
+				return &engine_types.PayloadStatus{Status: engine_types.ValidStatus, LatestValidHash: &latestValidHash}, nil
+			}
 		} else {
 			return &engine_types.PayloadStatus{Status: engine_types.SyncingStatus}, nil
 		}