Changing value of integer.toString() with Provider in flutter

Question

I am new to flutter.

I am trying to display an integer value. The value changes on some conditions. Now I am trying to update the widgets and the displaying value of the integer with Provider / ChangeNotifier but it doesn't work.

My tokens_provider.dart:

class TokenProvider extends ChangeNotifier {

  int value = 10;

  void decreaseTokens() async {
    final SharedPreferences prefs = await _prefs;
      value--;
      prefs.setInt('_tokens', value);
      notifyListeners();
  }
}

method where I call decreaseTokens:

Future<void> decreaseTokens() async {
    var tokens = context.read<TokenProvider>();
    if (tokens.value! > 0) tokens.decreaseTokens();
    final SharedPreferences prefs = await _prefs;
    await prefs.setInt('_tokens', tokens.value!);
    setState(() {});
  }

my Consumer Widget:

 @override
  Widget build(BuildContext context)  {
    return ChangeNotifierProvider<TokenProvider>(
        create: (context) => TokenProvider(),
        builder: (context, child) {
          return Consumer<TokenProvider>(
              builder: (context, tokens, child) {
                return Scaffold(
                  backgroundColor: Constants.backgroundColor,
                  appBar: AppBar(
                      leadingWidth: 100,
                      leading: Row(
                          crossAxisAlignment: CrossAxisAlignment.center,
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: [
                            SizedBox(width: 15),
                            Image.asset('assets/images/coin.png', scale: 4),
                            SizedBox(width: 3),
                            Text('${tokens.value}', style: TextStyle(
                                fontWeight: FontWeight.bold,
                                fontSize: 16,
                                color: Colors.green),),
                            SizedBox(width: 3),
                            Text("Token",
                              style: TextStyle(fontWeight: FontWeight.bold),)
                          ]
                      ),

But for some reason, it displays everytime 10 as value. It doesn't change at any action

I have also a log like this:

  Future<void> sendMessage() async {
    var tokens = context.read<TokenProvider>();
    if (messageController.text != "") {
      globals.counter -= 1;
      if(globals.counter == 0){AdManager.showIntAd();}
      if (tokens.value != 0) {
        decreaseTokens();
        log(tokens.value.toString());

In Console it displays after every action 1 less. So the logic should work, but I am definitely missing something with the provider but honestly I have no clue what it could be.