### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/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

14.0.0-beta.12

### What operating system are you using?

Windows

### Operating System Version

10.0.19042 Build 19042

### What arch are you using?

x64

### Last Known Working Electron version

13

### Expected Behavior

Window should be transparent

### Actual Behavior

Open a window with transparency enabled and delete the dom, the window will be white instead of transparent.
**Also seems like settings the backgroundColor property has no longer an effect.** I always see a white window

```
const {app, BrowserWindow} = require('electron')
const path = require("path");

function createWindow () {
	const mainWindow = new BrowserWindow({
		transparent: true,
		frame: false,
	})

	mainWindow.loadURL('https://example.com')
	mainWindow.webContents.openDevTools()
}

app.whenReady().then(createWindow)
```

### Testcase Gist URL

https://gist.github.com/e124340107f6c4a3ade8b36d98a16b9a

### Additional Information

_No response_
shell/browser/api/electron_api_web_contents.cc
double factor) {
  if (factor < std::numeric_limits<double>::epsilon()) {
    thrower.ThrowError("'zoomFactor' must be a double greater than 0.0");
    return;
  }
  auto level = blink::PageZoomFactorToZoomLevel(factor);
  SetZoomLevel(level);
}
double WebContents::GetZoomFactor() const {
  auto level = GetZoomLevel();
  return blink::PageZoomLevelToZoomFactor(level);
}
void WebContents::SetTemporaryZoomLevel(double level) {
  zoom_controller_->SetTemporaryZoomLevel(level);
}
void WebContents::DoGetZoomLevel(
    electron::mojom::ElectronBrowser::DoGetZoomLevelCallback callback) {
  std::move(callback).Run(GetZoomLevel());
}
std::vector<base::FilePath> WebContents::GetPreloadPaths() const {
  auto result = SessionPreferences::GetValidPreloads(GetBrowserContext());
  if (auto* web_preferences = WebContentsPreferences::From(ontents())) {
    base::FilePath preload;
    if (web_preferences->GetPreloadPath(&preload)) {
      result.emplace_back(preload);
    }
  }
  return result;
}
v8::Local<v8::Value> WebContents::GetWebPreferences(