Rebuild an array in PHP: merge array elements and save them to comma separated values

I have some trouble re-building a PHP array. I need to change it for printing a table to a PDF doc with tfPDF Library.

I tried it with foreach loops, array_walk, array_walk_recursive, array_chunk and array_slice – so far without success.

This is my array $data:

Array
(
    [file_id] => 1394
    [user_id] => 463466
    [periode] => 2022
    [costs] => 64.45
    [values] => Array
        (
            [457] => Array
                (
                    [1] => Array
                        (
                            [data_id] => 1
                            [supplier_id] => 457
                            [costs1] => 1000
                            [costs2] => 100
                            [group_name] => 7%
                        )

                    [140] => Array
                        (
                            [data_id] => 140
                            [supplier_id] => 457
                            [costs1] => 2000
                            [costs2] => 50
                            [group_name] => 19%
                        )

                    [197] => Array
                        (
                            [data_id] => 197
                            [supplier_id] => 457
                            [costs1] => 3000
                            [costs2] => 300
                            [group_name] => special
                        )

                )

            [430] => Array
                (
                    [490] => Array
                        (
                            [data_id] => 490
                            [supplier_id] => 430
                            [costs1] => 500
                            [costs2] => 30
                            [group_name] => new 4
                        )

                    [552] => Array
                        (
                            [data_id] => 552
                            [supplier_id] => 430
                            [costs1] => 7000
                            [costs2] => 250
                            [group_name] => new 5
                        )

                )

            [425] => Array
                (
                    [1106] => Array
                        (
                            [data_id] => 1106
                            [supplier_id] => 425
                            [costs1] => 10
                            [costs2] => 4
                            [group_name] => new 6
                        )

                )

        )

)

For the print function the follwing format would be the best:

$pdf->Row(array(
                        "data_id n" .
                        "data_id n" .
                        "data_id",
                        
                        "supplier_id n" .
                        "supplier_id n" .
                        "supplier_id",
                        
                        "costs1 n" .
                        "costs1 n" .
                        "costs1",
                        
                        "costs2 n" .
                        "costs2 n" .
                        "costs2",
                        
                        "group_name n" .
                        "group_name n" .
                        "group_name",
));

So I need to change the $data to an array like this:

Array
(
    [file_id] => 1394
    [user_id] => 463466
    [periode] => 2022
    [costs] => 64.45
    [values] => Array
        (
            [457] => Array
                (
                    [data_id] => 1, 140, 197
                    [supplier_id] => 457, 457, 457
                    [costs1] => 1000, 2000, 3000
                    [costs2] => 100, 50, 300
                    [group_name] => 7%, 19%, special
                )

            [430] => Array
                (
                    [data_id] => 490, 552
                    [supplier_id] => 430, 430
                    [costs1] => 500, 7000
                    [costs2] => 30, 250
                    [group_name] => new 4, new 5
                )

            [425] => Array
                (
                    [data_id] => 1106
                    [supplier_id] => 425
                    [costs1] => 10
                    [costs2] => 4
                    [group_name] => new 6
                )
        )

)

Can you help me?

The last step would be the comma separation like this:

array_walk($data['values'], function (&$val) {
    $val[] = implode(", ", $val[]);
});