Repository: flutter
Issue: SnackBar adds extra height for SafeArea when not needed
Labels: framework,f: material design,has reproducible steps,P2,team-design,triaged-design,found in release: 3.22,found in release: 3.23

### Steps to reproduce

Use a device with SafeArea at the bottom (like the iPhone 15 I used for testing), and click the FloatingActionButton

### Expected results

The SnackBar is shown without extra heights, as they are not necessary

### Actual results

An extra height is applied to the SnackBar, I believe caused by the SafeArea (since testing it on a rectangular "Motorola G22" device that does not have SafeArea underneath has no problem)

### Code sample

<details open><summary>Code sample</summary>

```dart
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const MyHomePage(),
      builder: (context, widget) {
        return Column(
          children: [
            Expanded(
              child: widget!,
            ),
            // Banner
            Container(
              height: 75,
              color: Colors.pinkAccent,
            ),
          ],
        );
      },
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: const Text('Flutter Demo Home Page'),
      ),
      body: null,
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(
              content: Text("This is a SnackBar"),
            )
          );
        },
        child: const Icon(Icons.add),
      ),
    );
  }
}
```

</details>


### Screenshots or Video

The first screenshot was taken without:
```dart
Container(
  height: 75,
  color: Colors.pinkAccent,
),
```
and it works correctly, because with iPhone 15 it requires SafeArea underneath and therefore it is good to add extra height to the SnackBar.

In the second screenshot I added that container (and then tested with the code I shared with you) and now it adds extra height when it's not needed.

<details open>
<summary>Screenshots / Video demonstration</summary>

| | |
| --------------- | --------------- |
<img width="400" src="https://github.com/flutter/flutter/assets/83022092/48743a20-2e36-443c-8ecc-ab41f3962e4a"> | <img width="400" src="https://github.com/flutter/flutter/assets/83022092/ec037fa0-423b-44f1-8fc9-64222629bf0b">

</details>

### Logs

<details open><summary>Logs</summary>

```console
[Paste your logs here]
```

</details>


### Flutter Doctor output

<details open><summary>Doctor output</summary>

```console
[✓] Flutter (Channel stable, 3.22.2, on macOS 14.5 23F79 darwin-arm64, locale it-IT)
[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 15.4)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2023.2)
[✓] VS Code (version 1.90.2)
[✓] Connected device (4 available)
[✓] Network resources

• No issues found!
```

</details>