Filament Repeater: How to Create Multiple Records from a Single Entry?

[
    ['item' => 'A'],
    ['item' => 'A'],
    ['item' => 'A'],
]

Repeater::make('cartonTransactions')
    ->relationship() // Relationship is set up correctly
    ->schema([
        Select::make('item')
            ->label('Item')
            ->options(Item::pluck('name', 'id'))
            ->required(),
        TextInput::make('quantity')
            ->numeric()
            ->minValue(1)
            ->required(),
    ])
    ->mutateRelationshipDataBeforeCreateUsing(function (array $data): array {
        // I want to create multiple records based on the quantity field.
        $quantity = (int) $data['quantity'];
        $item = $data['item'];

        $records = [];
        for ($i = 0; $i < $quantity; $i++) {
            $records[] = [
                'item' => $item,
            ];
        }
        // Returning an array of arrays instead of a single associative array.
        return $records;
    });