query laravel not working if pass variable in Where NOT IN

I’m trying to filter items from a database table
what I do is get the ids that I want to exclude and then through -> whereNotIn in laravel, I pass the ids

$idcontracts=array();
$idbike=array();
$biciCorretta = array();

$findcontract=Contract::whereRaw('? between data_inizio and data_fine', [$datainizio])->whereRaw('? between data_inizio and data_fine', [$datafine])->get();
        foreach ($findcontract as $key) {
            if (!in_array($key->id,$idcontracts)) {
                array_push($idcontracts,$key->id);
            }
        }
        
        foreach ($idcontracts as $idcontract) {
            $bike_contracts=DB::table('bike_contract')->where('contract_id',$idcontract)->get();
            foreach ($bike_contracts as $bike_contract) {
                if (!in_array($bike_contract->bike_id,$idbike)) {
                    array_push($idbike,$bike_contract->bike_id);
                }
            }
            
            
        }
        
        $notid=implode("', '",$idbike);

up to this point I have no problem.
the result of "implode" gives me the ids I want to remove

this is the result of $idbike and $notid:

this is the query I write to exclude the ids found:

$bikes = Bike::with('category')->whereNotIn('id', [$notid])->orderBy('category_id')->get();

the problem is that it doesn’t exclude me the ids passed with $notid

but if I manually pass the ids, it removes them instead:

$bikes = Bike::with('category')->whereNotIn('id', [40,41,34,36,39])->orderBy('category_id')->get();

am I doing something wrong?

>Solution :

You shouldn’t implode $notid, that makes it a string and Laravels whereNotIn() already does that for you.

->whereNotIn('id', $idbike)

And remove the $notid parameter, as it is not needed.