Undefined array key just for first key in array, every other key works fine. Codeigniter 4

So i am trying to import data from csv file to the database. Everything except first key in array works fine. All the rest data is inserted in db.

    $boltReport    = array();
    $count = 0;
    foreach($rows as $row) {
        if(!empty($row)){
            $boltReport[] = array_combine($header_row, $row);
        }
    }
    $boltReportTrimed = array();
    foreach($boltReport as $driver){
        if (!empty($driver['Telefonski_broj_vozaca'])){
            if($driver['Period'] != 'Period'){
                if(!empty($driver['Utilization'])){
                    $driver['report_for_week']= $week;
                    $boltReportTrimed[] = $driver;
                    $count++;
                    
                }
            }
        }
        
    }
    $driverData = new BoltReportModel();
    $findRecord = $driverData->where('report_for_week', $week)->countAllResults();

    $count1 = 0;
    foreach($boltReportTrimed as $driver){
            if($findRecord == 0){
                                
                if($driverData->insert($driver)){
                    $count1++;}
                }
            }

Here i am doing some filtering and using model to insert data in database. All the data except first item in array $boltReportTrimed is inserted in database.

So to debug i was using print_r and echo to check what data i have.

Here is the code

foreach($boltReportTrimed as $driver){
    if($findRecord == 0){
        echo '<pre>';
        print_r($driver);
        echo '</pre>';
        die();

        if($driverData->insert($driver)){
            $count1++;}
        }

With this code i get response like this:

Array
(
    [Vozac] => Ante Antunović
    [Telefonski_broj_vozaca] => +385958759630
    [Period] => Tjedan 2023-01-09 - 2023-01-15
    [Bruto_iznos] => 0.00
    [Otkazna_naknada] => 0.00
    [Naknada_za_rezervaciju_(placanje)] => 0.00
    [Naknada_za_rezervaciju_(odbitak)] => 0.00
    [Naknada_za_cestarinu] => 0.00
    [Bolt_naknada] => 0.00
    [Voznje_placene_gotovinom_(prikupljena_gotovina)] => 0.00
    [Popusti_na_voznje_na_gotovinu_od_Bolt_] => 0.00
    [Bonus] => 0.00
    [Nadoknade] => 
    [Povrati_novca] => 0.00
    [Napojnica] => 0.00
    [Tjedno_stanje_racuna] => 0.00
    [Sati_na_mrezi] => 0.20
    [Utilization] => 0.00
    [report_for_week] => 02
)

I know it’s almost all 0 but data is correct. First array item does not get inserted in database so i was trying to echo first item with this code:

foreach($boltReportTrimed as $driver){
    if($findRecord == 0){
        echo '<pre>';
        print_r($driver);
        echo $driver['Vozac'];
        echo '</pre>';
        die();
        
        if($driverData->insert($driver)){
            $count1++;}
        }

Here is one more thing i was trying:

                foreach($boltReportTrimed as $driver){
                        if($findRecord == 0){
                                            echo '<pre>';
                                            print_r($driver);
                                            //echo $driver['Vozac'];
                                            echo '</pre>';
                            $firstKey = array_key_first($driver);

                            var_dump($firstKey);                
                            
                            die();

And result is:

Array
(
    [Vozac] => Ante Antunović
    [Telefonski_broj_vozaca] => +385958733630
    [Period] => Tjedan 2023-01-09 - 2023-01-15
    [Bruto_iznos] => 0.00
    [Otkazna_naknada] => 0.00
    [Naknada_za_rezervaciju_(placanje)] => 0.00
    [Naknada_za_rezervaciju_(odbitak)] => 0.00
    [Naknada_za_cestarinu] => 0.00
    [Bolt_naknada] => 0.00
    [Voznje_placene_gotovinom_(prikupljena_gotovina)] => 0.00
    [Popusti_na_voznje_na_gotovinu_od_Bolt_] => 0.00
    [Bonus] => 0.00
    [Nadoknade] => 
    [Povrati_novca] => 0.00
    [Napojnica] => 0.00
    [Tjedno_stanje_racuna] => 0.00
    [Sati_na_mrezi] => 0.20
    [Utilization] => 0.00
    [report_for_week] => 02
)
string(8) "Vozac"

Now i got this error from the title:

ErrorException
Undefined array key “Vozac”

echoing any other key works fine and i get expected results
Help me please.