Source

File: wp-includes/post.php

function get_lastpostmodified( $timezone = 'server', $post_type = 'any' ) {
	/**
	 * Pre-filter the return value of get_lastpostmodified() before the query is run.
	 *
	 * @since 4.4.0
	 *
	 * @param string|false $lastpostmodified The most recent time that a post was modified,
	 *                                       in 'Y-m-d H:i:s' format, or false. Returning anything
	 *                                       other than false will short-circuit the function.
	 * @param string       $timezone         Location to use for getting the post modified date.
	 *                                       See get_lastpostdate() for accepted `$timezone` values.
	 * @param string       $post_type        The post type to check.
	 */
	$lastpostmodified = apply_filters( 'pre_get_lastpostmodified', false, $timezone, $post_type );

	if ( false !== $lastpostmodified ) {
		return $lastpostmodified;
	}

	$lastpostmodified = _get_last_post_time( $timezone, 'modified', $post_type );
	$lastpostdate     = get_lastpostdate( $timezone, $post_type );

	if ( $lastpostdate > $lastpostmodified ) {
		$lastpostmodified = $lastpostdate;
	}

	/**
	 * Filters the most recent time that a post on the site was modified.
	 *
	 * @since 2.3.0
	 * @since 5.5.0 Added the `$post_type` parameter.
	 *
	 * @param string|false $lastpostmodified The most recent time that a post was modified,
	 *                                       in 'Y-m-d H:i:s' format. False on failure.
	 * @param string       $timezone         Location to use for getting the post modified date.
	 *                                       See get_lastpostdate() for accepted `$timezone` values.
	 * @param string       $post_type        The post type to check.
	 */
	return apply_filters( 'get_lastpostmodified', $lastpostmodified, $timezone, $post_type );
}