The "All User Files" option is buggy if the application has the permission by default.
STEPS TO REPRODUCE
1. Find an application which has the "All User Files" permission by default
2. Modify the option to something other than "read/write"
3. Try to set it back to "read/write"
The "read/write" option disappears from the dropdown
The "read/write" option stays in the dropdown
KDE Plasma Version: 5.26.90
KDE Frameworks Version: 5.102.0
Qt Version: 5.15.8
Fixed via https://invent.kde.org/plasma/flatpak-kcm/-/merge_requests/91 and probably many other commits recently