Bug title - Color change in apptitle change breaking the font size in 175% display scale

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### Which version of the app?

WinUI 3 Gallery

### Description

Hi, I am trying to change the title text and the apptitle color without using a custom apptitle.
However, when I change any titleBar property, I've got the wrong title font size only for 175% display scale.

public MainWindow()
{
this.InitializeComponent();

var hWnd = WinRT.Interop.WindowNative.GetWindowHandle(this);
var windowId = Microsoft.UI.Win32Interop.GetWindowIdFromWindow(hWnd);
var appWindow = Microsoft.UI.Windowing.AppWindow.GetFromWindowId(windowId);

appWindow.Title = "TitleTest";
appWindow.TitleBar.BackgroundColor = Colors.Gray; //When the background is set, the app changes the 175%DisplayScale title font size to the 150%DisplayScale title font size.
}

Is there a way to change only the title and the titlebar background without using a custom titlebar to avoid this?

### Screenshots

_No response_

### Windows version

_No response_

### Additional context

_No response_

Start with the provided WinUI 3 Gallery reproduction using AppWindow.TitleBar.BackgroundColor, and compare the title-bar font at 150% and 175% display scaling. Trace the title-bar scaling behavior from the AppWindow and title-bar APIs; done means changing the title or background preserves the correct 175% font size without a custom title bar.

Written by the indexing model from the issue text.