The following restricted capabilities require approval before you can use them in your app: runFullTrust

What it means

runFullTrust is a restricted capability. Any packaged app that runs as a normal desktop process (full trust, medium integrity) has to declare it, so packaging tools add it for you. Microsoft Q&A answers confirm it's added automatically when you convert an EXE installer to MSIX or package a WinUI 3 app, and developers see it on new .NET MAUI projects too.

Every restricted capability needs approval for the Store. You ask for it on the Submission options page and testers review your reason during certification.

How to fix it

1. Keep runFullTrust if your app is a Win32, WPF, Windows Forms, WinUI 3 or other desktop app. Without it the package won't install. Remove it only if your app really runs in an AppContainer, like a UWP app.
2. On the submission's Submission options page, find Restricted capabilities and say why the app needs it and how it uses it. Microsoft asks for as much detail as possible. For example: "This is a desktop app packaged as MSIX. It runs as a full trust process, which requires runFullTrust."
3. If certification turns it down, the report says why. You can submit again with more detail, or with packages that don't declare the capability.

Does StoreFast check this?

Microsoft says you generally don't repeat the approval for updates unless you declare new capabilities. Once your first submission is approved in Partner Center, StoreFast can send the updates.