Doctrine Add column onSchemaCreateTable Event

I have some ManyToMany table relations. I'd like those to have a "created_at" field set when INSERT INTO.

Following Symfony and Doctrine Documentation, i tired this :

app/config/services_dev.yaml

[...]
    App\Event\Listener\ManyToManyListener:
        tags:
            - { name: doctrine.event_listener, event: onSchemaCreateTable }

app/src/Event/Listener/ManyToManyListener.php

[.....]

class ManyToManyListener implements EventSubscriber
{
    public function getSubscribedEvents()
    {
        return ['onSchemaCreateTable'];
    }

    public function onSchemaCreateTable(SchemaCreateTableEventArgs  $event)
    {
        $columns = $event->getTable()->getColumns();

        if (count($columns) <= 2 && !array_key_exists("created_at", $columns)) {
            $tableName = $event->getTable()->getName();
            $sql = "ALTER TABLE $tableName ADD COLUMN created_at TIMESTAMP(0) WITHOUT TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP;";
            $event->addSql($sql);
              //dump($sql);
        }
    }
}

I can dump my SQL code inside, it works.

I also tried this code (inside the if statement)

$event->getTable()->addColumn(
                "created_at",
                "datetime",
                ["default" => "CURRENT_TIMESTAMP"]
            );

This never execute the SQL statement. For example, while php bin/console doctrine:schema:update --dump-sql, I can't see my query.