### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/main/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/main/CODE_OF_CONDUCT.md) that this project adheres to.
- [X] I have searched the [issue tracker](https://www.github.com/electron/electron/issues) for a feature request that matches the one I want to file, without success.

### Electron Version

16.0.2

### What operating system are you using?

macOS

### Operating System Version

macOS Monterrey 12.0.1

### What arch are you using?

arm64 (including Apple Silicon)

### Last Known Working Electron version

13

_No response_

### Expected Behavior

This configuration should produce a vibrant window:

```ts
new BrowserWindow({
    width: 800,
    height: 600,
    backgroundColor: undefined,
    vibrancy: "sidebar",
    titleBarStyle: "hidden",
    webPreferences: {
      preload: path.join(__dirname, 'preload.js')
    }
  })
```

### Actual Behavior

The window has a white background.

As of Electron 16.x vibrancy works if `backgroundColor` is not set at all, but not if it's explicitly set to `undefined`. As a consequence, if the background color is set to any value, it's impossible to unset it later.

### Testcase Gist URL

_No response_

### Additional Information

What's interesting is that this option check returns `true` if the background color is explicitly set to `undefined`:

https://github.com/electron/electron/blob/bd10b19b0cdc46cdbadb570af89305e64541b679/shell/browser/api/electron_api_browser_window.cc#L50

But this one returns `false`:

https://github.com/electron/electron/blob/bd10b19b0cdc46cdbadb570af89305e64541b679/shell/browser/native_window.cc#L208

shell/browser/api/electron_api_browser_window.cc
web_contents()->WasOccluded();
  BaseWindow::OnWindowHide();
}
gin_helper::WrappableBase* BrowserWindow::New(gin_helper::ErrorThrower thrower,
                                              gin::Arguments* args) {
  if (!Browser::Get()->is_ready()) {
    thrower.ThrowError("Cannot create BrowserWindow before app is ready");
    return nullptr;
  }
  if (args->Length() > 1) {
    args->ThrowError();
    return nullptr;
  }
  gin_helper::Dictionary options;
  if (!(args->Length() == 1 && args->GetNext(&options))) {
    options = gin::Dictionary::CreateEmpty(args->isolate());
  }
  return new BrowserWindow(args, options);
}
void BrowserWindow::BuildPrototype(v8::Isolate* isolate,
                                   v8::Local<v8::FunctionTemplate> prototype) {
  prototype->SetClassName(gin::StringToV8(isolate, "BrowserWindow"));
  gin_helper::ObjectTemplateBuilder(isolate, prototype->PrototypeTemplate())
      .SetMethod("focusOnWebView", &BrowserWindow::FocusOnWebView)
      .SetMethod("blurWebView", &BrowserWindow::BlurWebView)
      .SetMethod("isWebViewFocused", &BrowserWindow::IsWebViewFocused)
      .SetProperty("webContents", &BrowserWindow::GetWebContents);
}
v8::Local<v8::Value> BrowserWindow::From(v8::Isolate* isolate,