Trying to send for a refresh token to laravel sanctum but showing error

Question

I added expiration time to sanctum config

'expiration' => now()->addMinutes(15),              // One hour
'rt_expiration' => now()->addDays(7),  // 7 Days

This is my function to authenticate the user

public function login(LoginRequest $loginRequest, Utils $utils)
    {

        if (!auth()->attempt(request()->only(['username', 'password']))) {
            return $utils->message( "error", "Invalid Username/Password", 401);
        }

        if (Auth::user()->role=="Agent")
            $user = Agent::where("user_id", Auth::user()->id)->firstOrFail();
        else
            $user = NewCustomer::where("user_id", Auth::user()->id)->firstOrFail();

        $loginRequest->get("device_id");
        $authUser = Auth::user();

        $success['token']  = $authUser->createToken('access_token', [TokenAbility::ACCESS_API->value], Carbon::now()->addMinutes(15));
        $success['refreshToken']  = $authUser->createToken('refresh_token', [TokenAbility::ISSUE_ACCESS_TOKEN->value], config('sanctum.rt_expiration'));
        $success['first_name'] =   $user->first_name;
        $success['last_name'] =  $user->last_name;
        $success['username'] =  $authUser->username;
        $success['wallet'] = number_format(Agent::where("user_id", $authUser->id)->value("wallet"), 2) ;
        return $utils->message("success", $success, 200);
    }

I am trying to send a refresh token

Route::post('/auth/refresh-token', function (Request $request) {
    $accessToken = $request->user()->createToken('access_token', [\App\Enums\TokenAbility::ACCESS_API->value], config('sanctum.expiration'));

    return ['token' => $accessToken->plainTextToken];
})->middleware([
    'auth:sanctum',
    'ability:'.\App\Enums\TokenAbility::ISSUE_ACCESS_TOKEN->value,
]);

But I am getting this error

 "message": "Unsupported operand types: Illuminate\\Support\\Carbon * int",
    "exception": "TypeError",
    "file": "/Users/mac/Documents/*************/vendor/nesbot/carbon/src/Carbon/Traits/Units.php",
    "line": 339,