php - Laravel download code stopped after a weekend

one text

So i am coding a application for users, a user is able to download 'files'. if a user clicks on the 'download' button it should run this code:

public function download(Request $request, int $fileId)
{
    $id = Auth::user();
    $userId = $id->id;
    $fullfile = File::find($fileId);    
    $downloadfile = File::find($fullfile, ['file'])->pluck('file')->last();    
    $checkPivot = DB::table('download')->where('file_id', '=', $fileId)->where('user_id', '=', $userId)->first();
    dd($checkPivot);
    if ($checkPivot == NULL) {
        $fullfile->userfile()->attach($id);
        return response()->download($downloadfile);
        return back();
    } else {
        return response()->download($downloadfile);
        return back();
    }
}

the code first checks for the user his role: (admin, partner, dealer) after that we are getting the user id itself. this is needed for the pivot table query under the If statement. then i will get the full row of the database table called 'file' in the row file. is a column called 'file' (like .docx, .pdf, .xlsx etc..), so we retrieve that. then i fire a query to check if the user already downloaded the file (by checking the pivot table) if not, then run the IF statement, otherwise run the ELSE statement.

even if i put the whole if else in psuedo code, it just keeps on downloading the file. but not placing a new row if needed in the pivot table.

before the weekend it worked 100% flawless. but now i just started up my pc and it stopped working for most part.

any tips on where to start? or what to look for, i never debug so i am really new to solving a bug like this