Source

File: wp-admin/includes/privacy-tools.php

function _wp_privacy_completed_request( $request_id ) {
	// Get the request.
	$request_id = absint( $request_id );
	$request    = wp_get_user_request( $request_id );

	if ( ! $request ) {
		return new WP_Error( 'privacy_request_error', __( 'Invalid request.' ) );
	}

	update_post_meta( $request_id, '_wp_user_request_completed_timestamp', time() );

	$result = wp_update_post(
		array(
			'ID'          => $request_id,
			'post_status' => 'request-completed',
		)
	);

	return $result;
}