TextBox height changes when text is entered if PlaceholderText is set

[g0g8rz]

Describe the bug

If you have a TextBox in a Auto-sizing grid row (and perhaps other situations) and this TextBox has PlaceholderText set, the TextBox will resize slightly when real text is entered.

Steps to reproduce the bug

Create a Grid with a textbox (code example below) and set PlaceholderText. Then run the code and enter text into the box.

Expected behavior

Height to remain the same

Screenshots

TextBox-PlaceholderText-Height-but.mp4

NuGet package version

WinUI 3 - Windows App SDK 1.6.5: 1.6.250205002

Windows version

Windows 11 (23H2): Build 22631

Additional context

Workaround is to set a MinHeight and the problem goes away