updateBatch(): Argument #2 ($index) must be of type string

Hello!

I am getting this exception :

CodeIgniter\Database\BaseBuilder::updateBatch(): Argument #2 ($index) must be of type ?string, array given
My code is this , its in a function inside my model.

PHP Code:

$db = $this->db;

    $builder = $db->table($this->table);
    $builder->updateBatch($data,['date','name', 'winner_name','runnerUp_name', 'titleAvgEloRating', 'matchID']); 


In the CI4 documentation the example :

PHP Code:

$data = [
    [
        'title'  => 'Title 1',
        'author' => 'Author 1',
        'name'  => 'Name 1',
        'date'  => 'Date 1',
    ],
    [
        'title'  => 'Title 2',
        'author' => 'Author 2',
        'name'  => 'Name 2',
        'date'  => 'Date 2',
    ],
];
$builder->updateBatch($data, ['title', 'author']); 


Does not appear to show second argument as a String, but as an array. I am doing something wrong? Or is there a bug here?