[Rendering] Adaptive card with svg background looks great on web; bad in the new winui3 widget board

Target Platforms

Other

SDK Version

Windows Widget Board; no idea

Application Name

MyCollegueas

Problem Description

SVG background looks great in the web renderer while in the winui3 it's nog looking so good. I noticed this difference while building widgets for windows 11. See screenshot and card json below

Screenshots

In the designer; this is also how it looked in the old web based widget board

In the new winui3 widget board

as you see the background is no longer filling the entire card

Card JSON

Card json
`
{
  "type": "AdaptiveCard",
  "$schema": "http://adaptivecards.io/schemas/adaptive-card.json",
  "version": "1.6",
  "body": [

  ],
  "backgroundImage": {
    "url": "${if(equals($host.hostTheme,'light'), $root.LightBackground, $root.DarkBackground)}"
  }
}
`

Data json
`
{
  "LightBackground": "data:image/svg+xml;base64,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",
  "DarkBackground": "data:image/svg+xml;base64,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",
}
`

Sample Code Language

No response

Sample Code

No response

Start by reproducing the supplied card JSON in the WinUI3 widget board and compare its SVG background rendering with the web renderer shown in the screenshots. No source file or test is identified in the issue; done means the SVG background fills the card consistently in the WinUI3 renderer without regressing the web behavior.