Sandboxing stopped: All installed Flathub apps have access to all folders and files outside their sandbox. What could cause this challenge?

Hello @CodedOre . My replies are below.

But, if you want to confirm the sandbox is really working, here is a quick test you can do:

Run flatpak run --command=bash org.freedesktop.Platform//25.08.

Thanks for your suggestion . I will try this when I am available. Then post the result here.

Yes, an Flatpak can gain default access to selected folders by having a filesystem permission set.

All global filesystem Flatpak permissions are denied. Same for the app filesystem Flatpak permissions. They are all denied. Detailed configuration about this is in my original post up above. Maybe my original post was not clear about this.