Repository: flutter
Issue: fontWeight affects variable font even with FontVariation
Labels: framework,a: typography,has reproducible steps,P3,team-engine,triaged-engine,found in release: 3.13,found in release: 3.16

### Is there an existing issue for this?

- [X] I have searched the [existing issues](https://github.com/flutter/flutter/issues)
- [X] I have read the [guide to filing a bug](https://flutter.dev/docs/resources/bug-reports)

### Steps to reproduce

1. Add a `fontFamily` that uses a variable weight font to a `TextStyle`.
2. Add a `FontVariation` for the weight to `TextStyle`.
3. Add a `FontWeight` of `w600` or higher to the `TextStyle`.
4. Render `Text` component using the style.

### Expected results

I expect `fontWeight` to have no effect.

### Actual results

The rendered texts is bolder than the weight specified by the `FontVariation`.

I can confirm this happens on Linux, Android, and Desktop Web.

### Code sample

<details><summary>Code sample</summary>

lib/main.dart
```dart
import 'dart:ui';

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key});

  @override
  Widget build(BuildContext context) {
    const baseStyle = TextStyle(
      fontFamily: "Noto Sans JP",
      fontSize: 12.0,
    );

    return Scaffold(
        appBar: AppBar(
          title: const Text("Variable Fonts"),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              ..._fontWeightsOf(
                baseStyle.copyWith(
                    fontVariations: [const FontVariation("wght", 400)]),
              ),
              ..._fontWeightsOf(
                baseStyle.copyWith(
                    fontVariations: [const FontVariation("wght", 900)]),
              ),
            ],
          ),
        ));
  }

  List<Widget> _fontWeightsOf(TextStyle style) {
    final fontWeights = [
      FontWeight.w100,
      FontWeight.w200,
      FontWeight.w300,
      FontWeight.w400,
      FontWeight.w500,
      FontWeight.w600,
      FontWeight.w700,
      FontWeight.w800,
      FontWeight.w900,
    ];

    return fontWeights.map((weight) {
      final newStyle = style.copyWith(fontWeight: weight);
      return Text("$newStyle with ${newStyle.fontVariations}", style: newStyle);
    }).toList();
  }
}
```

pubspec.yaml
```yaml
name: variable_fonts_debug
description: A new Flutter project.
publish_to: 'none'

version: 1.0.0+1

environment:
  sdk: '>=3.1.3 <4.0.0'

dependencies:
  flutter:
    sdk: flutter

  cupertino_icons: ^1.0.2

dev_dependencies:
  flutter_test:
    sdk: flutter

  flutter_lints: ^2.0.0

flutter:

  uses-material-design: true

  fonts:
    - family: Noto Sans JP
      fonts:
        - asset: fonts/NotoSansJP.ttf
```
fonts/NotoSansJP.ttf

Used this font: https://fonts.google.com/noto/specimen/Noto+Sans+JP

</details>


### Screenshots or Video

<details>
<summary>Screenshots / Video demonstration</summary>


![Screenshot from 2023-10-18 10-30-03](https://github.com/flutter/flutter/assets/148174446/43c8fb80-dddb-4089-b92d-4fa2a8ff8543)



</details>


### Flutter Doctor output

<details><summary>Doctor output</summary>

```console
[✓] Flutter (Channel stable, 3.13.7, on Pop!_OS 22.04 LTS 6.5.4-76060504-generic, locale
    en_US.UTF-8)
    • Flutter version 3.13.7 on channel stable at /home/work/snap/flutter/common/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 2f708eb839 (8 days ago), 2023-10-09 09:58:08 -0500
    • Engine revision a794cf2681
    • Dart version 3.1.3
    • DevTools version 2.25.0

[✓] Android toolchain - develop for Android devices (Android SDK version 33.0.2)
    • Android SDK at /home/work/Android/Sdk
    • Platform android-33, build-tools 33.0.2
    • Java binary at: /usr/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.8.1+1-Ubuntu-0ubuntu122.04)
    • All Android licenses accepted.

[✗] Chrome - develop for the web (Cannot find Chrome executable at google-chrome)
    ! Cannot find Chrome. Try setting CHROME_EXECUTABLE to a Chrome executable.

[✓] Linux toolchain - develop for Linux desktop
    • clang version 10.0.0-4ubuntu1
    • cmake version 3.16.3
    • ninja version 1.10.0
    • pkg-config version 0.29.1

[!] Android Studio (not installed)
    • Android Studio not found; download from
      https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/linux#android-setup for
      detailed instructions).

[✓] VS Code (version 1.83.1)
    • VS Code at /usr/share/code
    • Flutter extension can be installed from:
      🔨 https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter

[✓] Connected device (2 available)
    • Pixel 5a (mobile) • 17081JECB12298 • android-arm64 • Android 14 (API 34)
    • Linux (desktop)   • linux          • linux-x64     • Pop!_OS 22.04 LTS
      6.5.4-76060504-generic

[✓] Network resources
    • All expected network resources are available.

! Doctor found issues in 2 categories.
```

</details>