Unprivileged user namespaces / kernel.unprivileged_userns_clone / Can not run flatpak apps / AppImages after Kicksecure update

This is good to have and kept as default, something else should be figured out on how to make flatpak work.

Alpinelinux using the same kernel option:

But they say if you have flatpak permission issue just " add your user to the flatpak group."

https://wiki.alpinelinux.org/wiki/Flatpak#Permission_errors

Why turning off this option is not solution:

Workaround, worked:

[user ~]% sudo sysctl -w kernel.unprivileged_userns_clone=1
kernel.unprivileged_userns_clone = 1
[user ~]% flatpak install org.mozilla.firefox
Looking for matches…
Required runtime for org.mozilla.firefox/x86_64/stable (runtime/org.freedesktop.Platform/x86_64/23.08) found in remote flathub
Do you want to install it? [Y/n]: n 
error: The application org.mozilla.firefox/x86_64/stable requires the runtime org.freedesktop.Platform/x86_64/23.08 which is not installed
zsh: exit 1     flatpak install org.mozilla.firefox
[user ~]% flatpak install io.freetubeapp.FreeTube
Looking for matches…
Required runtime for io.freetubeapp.FreeTube/x86_64/stable (runtime/org.freedesktop.Platform/x86_64/23.08) found in remote flathub
Do you want to install it? [Y/n]: y

io.freetubeapp.FreeTube permissions:
    ipc        network                pulseaudio             x11
    dri        file access [1]        dbus access [2]        bus ownership [3]

    [1] xdg-download
    [2] org.freedesktop.PowerManagement, org.freedesktop.ScreenSaver, org.gnome.SessionManager,
        org.gnome.SettingsDaemon
    [3] org.mpris.MediaPlayer2.chromium.*, org.mpris.MediaPlayer2.freetube


        ID                                     Branch         Op    Remote    Download
 1. [✓] org.freedesktop.Platform.GL.default    23.08          i     flathub   164.6 MB / 163.8 MB
 2. [✓] org.freedesktop.Platform.GL.default    23.08-extra    i     flathub    22.6 MB / 163.8 MB
 3. [✓] org.freedesktop.Platform.Locale        23.08          i     flathub    17.9 kB / 371.6 MB
 4. [✓] org.freedesktop.Platform.openh264      2.2.0          i     flathub     1.2 MB / 944.3 kB
 5. [✓] org.freedesktop.Platform               23.08          i     flathub   250.0 MB / 230.9 MB
 6. [✓] io.freetubeapp.FreeTube                stable         i     flathub   123.4 MB / 114.8 MB

Installation complete.
[user ~]%