I tried this on Windows, and the client appears to continue working, but I want to understand if this behavior is guaranteed or just a fluke:

using (var listener = new TcpListener(IPAddress.Loopback, 34346)) {
    listener.Start();

    // client
    Task.Run(async () => {
        using var client = new TcpClient();
        await client.ConnectAsync(IPAddress.Loopback, 34346);
        await using var stream = client.GetStream();
        await Task.Delay(TimeSpan.FromSeconds(30));
        stream.WriteByte(42);
    });
    
    using var client = await listener.AcceptTcpClientAsync();

    listener.Stop();
    listener.Dispose();
    log.LogInformation("Disposed listener");

    await using var stream = client.GetStream();
    log.LogInformation("{Byte}", stream.ReadByte());
}

Prints:

Disposed listener
42