Rollback method does not work in mysqli extended class

Hello, Because of the PHP version on the server, the fetch all and mysqli begin_transaction methods do not work. To solve this, I created another connection class by extending the MySQLi class and instantiating it.

<?php
namespace App\DB;

class MySQLiConnector extends \mysqli
{
    function __construct($host, $user, $pass, $db)
    {
        parent::__construct($host, $user, $pass, $db);
    }

    public function query($query) {
        if( !$this->real_query($query) ) {
            return false;
        }

        return new MySQLiResultSet($this);
    }

    public function begin_transaction($flags = NULL, $name = NULL)
    {
        $this->autocommit(FALSE);
    }
}

and the mysqliresultset class

<?php
namespace App\DB;

class MySQLiResultSet extends \MySQLi_Result
{
    public function fetch()
    {
        return $this->fetch_assoc();
    }

    public function fetch_all()
    {
        $rows = array();
        while($row = $this->fetch())
        {
            $rows[] = $row;
        }
        return $rows;
    }
}

?>

However, when I try to use the mysqli-> rollback () method when a given query fails, it does not work, the changes are saved anyway.

The code where I try to run the rollback:

        $this->db->begin_transaction();

        $query1 = $this->db->query($sql1);
        $query2 = $this->db->query($sql2);
        $query3 = $this->db->query($sql3);


        if (!$query1 || !$query2 || !$query3) {
           $this->db->rollback();
           throw new ModelException("Erro da base de dados. -> ".$this->db->error);
        } else {
           $this->db->commit();
           return true;
        }

Is there any way to solve this problem?