Magento2 query displaying perfect result in database but wrong in collection while sorting by created_at

Magento2 query displaying perfect result in database but wrong in collection while sorting by created_at

Query

SELECT `e`.*, `cat_index`.`position` AS `cat_index_position`, `price_index`.`price`, `price_index`.`tax_class_id`, `price_index`.`final_price`, IF(price_index.tier_price IS NOT NULL, LEAST(price_index.min_price, price_index.tier_price), price_index.min_price) AS `minimal_price`, `price_index`.`min_price`, `price_index`.`max_price`, `price_index`.`tier_price`, IFNULL(review_summary.reviews_count, 0) AS `reviews_count`, IFNULL(review_summary.rating_summary, 0) AS `rating_summary` FROM `catalog_product_entity` AS `e` INNER JOIN `catalog_category_product_index_store1` AS `cat_index` ON cat_index.product_id=e.entity_id AND cat_index.store_id=1 AND cat_index.visibility IN(2, 4) AND cat_index.category_id=8 INNER JOIN `catalog_product_index_price` AS `price_index` ON price_index.entity_id = e.entity_id AND price_index.customer_group_id = 0 AND price_index.website_id = '1' LEFT JOIN `review_entity_summary` AS `review_summary` ON e.entity_id = review_summary.entity_pk_value AND review_summary.store_id = 1 AND review_summary.entity_type = (SELECT `review_entity`.`entity_id` FROM `review_entity` WHERE (entity_code = 'product')) ORDER BY `e`.`created_at` DESC

For sorting

$this->_collection
      ->getSelect()
        ->order('e.created_at');