human_time_diff() returns "48 years ago" for all comments (ok)

https://wordpress.stackexchange.com/questions/278040/human-time-diff-returns-48-years-ago-for-all-comments

$args = array(
        'number'  => '4',
        'post_id' => $id, // use post_id, not post_ID
);

$comments = get_comments( $args );

foreach ( $comments as $comment ) :

    // get the comments contents    

    echo $comment->comment_content;

    // human readable time when it was posted
    //
    // this is where we get the "48 years" as when it was posted
    //

    echo human_time_diff( echo human_time_diff( strtotime( $comment->comment_date ), current_time( 'timestamp', 1 ) );, current_time( 'timestamp', 1 ) );

endforeach;