TaxonomyTermEntityClone.php

<?php

namespace Drupal\entity_clone\EntityClone\Content;

use Drupal\Core\Entity\EntityInterface;

/**
 * Class Taxonomy Term Entity Clone.
 */
class TaxonomyTermEntityClone extends ContentEntityCloneBase {
    
    /**
     * {@inheritdoc}
     */
    public function cloneEntity(EntityInterface $entity, EntityInterface $cloned_entity, array $properties = [], array &$already_cloned = []) {
        
        /** @var \Drupal\core\Entity\ContentEntityInterface $cloned_entity */
        // Enforce a parent if the cloned term doesn't have a parent.
        // (First level of a taxonomy tree).
        if (!isset($cloned_entity->parent->target_id)) {
            $cloned_entity->set('parent', 0);
        }
        return parent::cloneEntity($entity, $cloned_entity, $properties);
    }

}