Why i haven`t the right input for my MySql query from my Array?

i have a Form with a table like this:

The projects can be from 1 up to 10.

Here is my code:

    $postarray = array();

foreach ($_POST as $field => $value) {


    $postdata = array($field => $value);
    array_push($postarray, $postdata);
    
}

$count = count($postarray);
$countcalculation = $count/ 7;

$output = array_chunk($postarray, $countcalculation);

$input= new Test\Hours\HoursEntry();
$input= $input->hoursentry($output);

Here is my output:

    Array
    (
        [0] => Array
            (
                [0] => Array
                    (
                        [day_0] => 2022-06-27
                    )
    
                [1] => Array
                    (
                        [project1_0] => 3
                    )
    
                [2] => Array
                    (
                        [project2_0] => 5
                    )
                [3] => Array
                    (
                        [project1_n] => 
                    )
    
                [4] => Array
                    (
                        [holiday_0] => 
                    )
    
                [5] => Array
                    (
                        [ill_0] => 
                    )
    
        [1] => Array
            (
                [0] => Array
                    (
                        [day_1] => 2022-06-28
                    )
    
                [1] => Array
                    (
                        [project1_1] => 1
                    )
    
                [2] => Array
                    (
                        [project2_1] => 2
                    )

                [3] => Array
                    (
                        [projectn_1] => 2
                    )
    
    
                [4] => Array
                    (
                        [holiday_1] => 
                    )
    
                [5] => Array
                    (
                        [ill_1] => 8
                    )
    
            )
)

I need a input in my Database like this:

Here is my try to write into the database:

$i = 0;

foreach ($output as $postdata) {

        foreach ($postdata as $post => $p) {

            $count = count($postdata);

            foreach ($p as $input => $value) {

                $var[$i] = $value;
                $name[$i] = $input;
                $i++;
            }

                $day = date_format(new DateTime($var[0]), 'Y.m.d');
                $ill = $var[$count];
                $holiday = $var[$count - 1];

            for ($z = 1; $z <= $count - 2; $z++) {

                $hours = $var[$z];
                $project = $name[$z];

            
               // The Echo is to simulate the MySql query
                echo $tag . '</br>';
                echo $hours. '</br>';
                echo $project . '</br>';
             }   


        
          // The Echo is to simulate the MySql query
             echo $ill. '</br>';
             echo $holiday. '</br>';
            }

    }