Only variant asset being used

Project structure:

my_project:
  - lib
  - assets
      - dark/logo.png
      - logo.png

pubspec.yaml:

flutter:
  assets:
    - assets/logo.png

Code:

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      themeMode: ThemeMode.light,
      home: Scaffold(
        body: Center(
          child: Image.asset('assets/logo.png'),
        ),
      ),
    );
  }
}

Whenever I run the app, the variant inside the assets/dark directory is being used, not the main asset. I've tried switching between thememodes but that has not effect.