Don't use 'BuildContext's across async gaps in Flutter warning doesn't go away

Flutter gives me the warning "Don’t use ‘BuildContext’s across async gaps. Try rewriting the code to not use the ‘BuildContext’, or guard the use with a ‘mounted’ check". The warning is in my app twice and I can’t make any of them go away by adding a "mounted guard". Below is a full standalone app that demonstrates a simple version of my app. Can you please show me what is the ideal way of solving this problem, and if it’s the "mounted guard", where should I put them?

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Search History Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Search History'),
      ),
      body: Center(
        child: ElevatedButton(
          onPressed: () {
            clearEnglishHistory(context);
          },
          child: const Text('Clear History'),
        ),
      ),
    );
  }

  Future<void> clearEnglishHistory(BuildContext context) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    bool confirmClear = await showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: const Text('Confirmation'),
          content: const Text('Do you really want to clear search history?'),
          actions: <Widget>[
            TextButton(
              onPressed: () {
                Navigator.of(context).pop(false);
              },
              child: const Text('No'),
            ),
            TextButton(
              onPressed: () {
                Navigator.of(context).pop(true);
              },
              child: const Text('Yes'),
            ),
          ],
        );
      },
    );

    if (confirmClear == true) {
      await prefs.remove('english history');
      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
        content: Text('History cleared'),
      ));
    }
  }
}