Access Denied to start any process (WinUI 3)

Question

I can't launch any app because the code below shows this error: System.ComponentModel.Win32Exception: 'Access Denied'

var process = Process.Start(@"C:\foo.exe");

I've already tested it with countless other applications, such as winword, mspaint, calc, notepad, etc, and they all get the same error message.
Even opening Visual Studio with administrator privileges this error message appears.
I don't know if it's something in Visual Studio (I'm using the latest preview version) or if it could be something in WinUI 3 itself.