UserEntityClone.php

<?php

namespace Drupal\entity_clone\EntityClone\Content;

use Drupal\Core\Entity\EntityInterface;

/**
 * Class ContentEntityCloneBase.
 */
class UserEntityClone extends ContentEntityCloneBase {
    
    /**
     * {@inheritdoc}
     */
    public function cloneEntity(EntityInterface $entity, EntityInterface $cloned_entity, array $properties = [], array &$already_cloned = []) {
        
        /** @var \Drupal\user\UserInterface $cloned_entity */
        $cloned_entity->set('name', $cloned_entity->getAccountName() . '_cloned');
        return parent::cloneEntity($entity, $cloned_entity, $properties);
    }

}