api-platform unwanted field update on custom operation - symfony

Question

There is an app with api-platform on top of symfony 4. I have created a custom operation as recommended.
The Entity
* #Api\ApiResource(
* normalizationContext={"groups"={"read_importation_demand"}},
* denormalizationContext={"groups"={"write_importation_demand"}},
* itemOperations={
* "get",
* "put",
* "delete",
* "workflow"={
* "method"="POST",
* "path"="/importation_demands/{id}/workflow",
*
* "controller"=ImportationWorkflowController::class,
* }
* })
The Controller
public function __invoke(ImportationDemand $data, Request $request): ImportationDemand
{
$requestData = json_decode($request->getContent(), true);
$request->request->replace($requestData);
$workflow = $this->workflowsRegistry->get($data, 'presentacion_oferta');
$transicion = $request->get('transition');
$workflow->apply($data, constant("App\Enum\ImportationDemandWorkflowEnum::$transicion"));
$this->manager->flush();
return $data;
}
What I'm doing here is receiving a description and transition parameters to set on the workflow entity. The problem is that when I flush to database the description attribute in ImportationDemand is setted with the value of the description field received. It suposed to be setted only in the ImportationDemandWorkflow entity but is settedin both. As you can see in the code I never set the ImportationDemand description field.
Transition event listener
public function onWorkflowPresentacionOfertaEntered(WorkflowEvent $event)
{
$request = $this->container->get('request_stack')->getCurrentRequest();
$username = $this->container->get('security.token_storage')->getToken()->getUsername();
$user = $this->manager->getRepository(User::class)->loadUserByUsername($username);
/** #var ImportationDemand $solicitud */
$solicitud = $event->getSubject();
$workflow = new ImportationDemandWorkflow();
$workflow->setStatus($solicitud->getStatus())
->setDescription($request->get('description', 'No se introdujo una descripción para esta operación'))
->setAction($event->getTransition()->getName())
->setDoneAt(new \DateTime())
->setPerformer($user);
$solicitud->addWorkflow($workflow);
}
The spected behavior is that the description field would be setted only in the entity ImportationDemandWorkflow.
Why is api-platform updating the description field if I'm, allegendly, taking control of the performed operation?
Thanks in advance!