void OnClick(object sender, EventArgs e)
{
    Button newButton = new()
    {
        Text = "New Button",
        BackColor = Color.White,
        ForeColor = Color.Black,
        Size = new Size(100, 50),
        TextAlign = ContentAlignment.MiddleCenter
    };

    newButton.Click += (s, e) => NewButtonOnClick(newButton);

    flowLayoutPanel.Controls.Add(newButton);
    newButton.Show();
}

void OnClick(object sender, EventArgs e)
{
    Button newButton = new()
    {
        Text = "New Button",
        BackColor = Color.White,
        ForeColor = Color.Black,
        Size = new Size(100, 50),
        TextAlign = ContentAlignment.MiddleCenter
    };

    newButton.Click += (s, e) => NewButtonOnClick(newButton);

    flowLayoutPanel.Controls.Add(newButton);
    newButton.Show();
}