Codeigniter 4 Query Builder loses SELECT and WHERE condition while executing once more

I am using Codeigniter 4 Query Builder. Following is code to retrieve data from the database

    public function get_data()
    {
        $where = [
            'username' => 'admin'
        ];
        $this->_builder = $this->_db->table('pf_user_master s');
        $this->_builder->join('pf_role_master r', 'r.role_id = s.role_id');
        $this->_builder->select('username, first_name, last_name, mobile, email, r.role_name, s.status');
        if (is_array($where) && !empty($where)) {
            $this->_builder->where($where);
        }
        $first= $this->_builder->get()->getResultArray();
        print_r($first);
        $second= $this->_builder->get()->getResultArray();
        print_r($second);
        exit;
    }

I am getting the following output:

In variable $first I am getting output as expected

Array
(
    [0] => Array
        (
            [username] => admin
            [first_name] => Fisrt
            [last_name] => Last
            [mobile] => 
            [email] => first.last@gmail.com
            [role_name] => Admin
            [status] => 1
        )

)

But in variable $second it Query Builder loses SELECT, WHERE condition and also JOIN. And prints the output as follows:

Array
(
    [0] => Array
        (
            [user_id] => 1
            [username] => admin
            [password] => 21232f297a57a5a743894a0e4a801fc3
            [first_name] => First
            [last_name] => Last
            [mobile] => 
            [email] => first.last@gmail.com
            [role_id] => 1
            [status] => 1
            [created_by] => 
            [created_date] => 2020-09-08 19:30:52
            [updated_by] => 
            [updated_date] => 2020-09-08 19:32:42
        )

    [1] => Array
        (
            [user_id] => 2
            [username] => superadmin
            [password] => 21232f297a57a5a743894a0e4a801fc3
            [first_name] => NewFirst
            [last_name] => NewLast
            [mobile] => 
            [email] => new.new@gmail.com
            [role_id] => 1
            [status] => 1
            [created_by] => 
            [created_date] => 2020-09-08 21:51:42
            [updated_by] => 
            [updated_date] => 
        )

)

As mentioned by TimBrownlaw I changed $first= $this->_builder->get()->getResultArray(); to $first= $this->_builder->get(NULL, 0 , false)->getResultArray(); and it worked for me as it didn't reset the query as third parameter of get() is for resetting the query