Flutter leaking stateless widgets?

I know this sounds crazy, so maybe someone can point to me where am I wrong and maybe if I misunderstand some basic way Flutter works.

Here is some very basic code.

Run the app, click on the Floating Action Button and back 5 times. What I would expect is that BarPage is now gone from the memory.

Open Flutter Dev Tools, Memory tab and do a heap dump, check your instances. Here is what I got. 2 instances of BarPage still in memory. I did 3 separate dumps in case GC didn't trigger or something.

Here is the code

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: HomePage(),
      onGenerateRoute: (RouteSettings settings) {
        final args = settings.arguments;
        switch (settings.name) {
          case "/bar":
            return MaterialPageRoute(builder: (_) => BarPage());
        }
      },
    );
  }
}

class HomePage extends StatelessWidget {
  HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home screen'),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          Navigator.of(context).pushNamed("/bar");
        },
        child: const Icon(Icons.navigation),
        backgroundColor: Colors.green,
      ),
    );
  }
}

class BarPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Bar screen'),
      ),
    );
  }
}