Blazor, event listener as inline delegate or handler in @functions section

I got different reaction (output in console) when using inline delegate or when implementing a handler in @functions section. I don't understand why! Is that a bug or something is missing me?

<input type="text" onkeyup="@(e => Console.Write(e.Key))" />

It gives me immediate output in console. But when I use a handler like this, I got nothing:

<input type="text" onkeyup="@showKey"/>
@functions{
    void showKey(UIKeyboardEventArgs e){
        Console.Write(e.Key);
    }
}