I'm not sure whether it's a bug or a feature. But Firefox and browsers based on it may not update correctly if they don't have access to default desktop.
The problem is when they update or just restart they explicitly use winsta0/default for window station and desktop. So if they're intended to be executed on a different desktop and have no access to the default desktop, they'll terminate without even actually starting. Not sure why they made it work this way as besides this thing everything seems to work OK on a different desktop.
So take care if you write multi-desktop software. This issue was found several months ago, it wasn't fixed then. I haven't checked it since.