ThemeProvider does not return V2 theme in SingleWebPartAppPage

Target SharePoint environment

SharePoint Online

What SharePoint development model, framework, SDK or API is this about?

💥 SharePoint Framework

Developer environment

Windows

What browser(s) / client(s) have you tested

• 💥 Internet Explorer
• 💥 Microsoft Edge
• 💥 Google Chrome
• 💥 FireFox
• 💥 Safari
• mobile (iOS/iPadOS)
• mobile (Android)
• not applicable
• other (enter in the "Additional environment details" area below)

Additional environment details

• browser version v139
• SPFx version v1.21.1
• Node.js version v22.15.0

Describe the bug / error

Based on the documentation provided here:
https://learn.microsoft.com/en-us/javascript/api/sp-component-base/themeprovider?view=sp-typescript-latest#@microsoft-sp-component-base-themeprovider-trygetthemev2-member(1)

When this method is called on a sample article page, it returns proper theme, however when you try and call this method in SingleWebPartAppPage page layout, it returns undefined

Steps to reproduce

1. Create Hello World webpart
2. update supported hosts

  "supportedHosts": [
    "SharePointWebPart",
    "TeamsPersonalApp",
    "TeamsTab",
    "SharePointFullPage"
  ]

3. consume theme provider

//onInit
   this.themeProvider = this.context.serviceScope.consume(ThemeProvider.serviceKey);

//onRender
console.log(this.themeProvider.tryGetThemeV2())

4. Create article page, add webpart, observe that console.log returns data
5. Create app page, observe that console.log returns undefined

Expected behavior

There should be no difference, and it should return data, however I might be wrong and missed this part in the docs.