Column not found: 1054 Unknown column '0' in 'field list' [ Laravel ]

I'm using Laravel 7 try to make update Array Data in Laravel Controller

This my Controller

$unit_numbers =  $request->input('namavariant', []);    
$variantunits =[];
foreach ($unit_numbers as $indexs => $unitx) {
 $variantunits[] = [
     "produk_id" => $produk_id,
     "namavariant" => $request->namavariant[$indexs],
     "isivariant" => $request->isivariant[$indexs],
     'created_at' => Carbon::now(),
     'updated_at' => Carbon::now(),
     'username' =>  session()->get('username')
 ];
}
if($request->input('namavariant', []) != NULL){  
variant::where('produk_id','=', $produk_id)->update($variantunits);
}

this is input file from my form : Updatepages.blade.php

                  <label for="exampleInputEmail1">Nama Variasi</label>
                          <input type="text" class="form-control" id="customFieldName" name="namavariant[]" value="{{$vr->namavariant}}" placeholder="Cth : Size" /> &nbsp;
                   <label for="exampleInputEmail1">Pilihan</label>
                          <input type="text" class="form-control" id="customFieldValue" name="isivariant[]" value="{{$vr->isivariant}}" placeholder="Cth: XXL,XL,L,M"/> &nbsp;
                          <a href="javascript:void(0);" class="addCF">Add New</a>
                    </div>

when i'm update the data array i got errors " Column not found: 1054 Unknown column '0' in 'field list ", Maybe anyone know about this problem.

Thanks you

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