Why does a Skype installation on Linux via Flatpak require downloading > 1 GB of data?

I recently installed the current version of Skype on my OpenSuSE Leap 15.6 machine via Flatpak (as MS's original Zypper repo apparently no longer exists). It was successful, but Flatpak downloaded 1.15 GB of data, of which only 193,1 MB are the Skype client itself:

╭─jacek@epica ~  
╰─➤  sudo flatpak install com.skype.Client                                                                4 ↵
Suchen nach Übereinstimmungen …
Required runtime for com.skype.Client/x86_64/stable (runtime/org.freedesktop.Platform/x86_64/24.08) found in remote flathub
Möchten Sie es installieren? [Y/n]: 

com.skype.Client Berechtigungen:
    ipc              network                 pulseaudio              x11
    devices          file access          dbus access          system dbus access 

     xdg-documents:ro, xdg-download, xdg-music:ro, xdg-pictures:ro, xdg-videos:ro
     com.canonical.AppMenu.Registrar, org.freedesktop.Notifications, org.freedesktop.ScreenSaver,
        org.freedesktop.secrets, org.gnome.GConf, org.gtk.Notifications, org.kde.StatusNotifierWatcher
     org.bluez, org.freedesktop.NetworkManager, org.freedesktop.login1

       KENNUNG                                  Zweig          Op     Gegenstelle     Herunterladen
 1. [✓] org.freedesktop.Platform.GL.default      24.08          i      flathub         157,7 MB / 158,0 MB
 2. [✓] org.freedesktop.Platform.GL.default      24.08extra     i      flathub          21,1 MB / 158,0 MB
 3. [✓] org.freedesktop.Platform.Locale          24.08          i      flathub           1,6 MB / 379,1 MB
 4. [✓] org.freedesktop.Platform.openh264        2.4.1          i      flathub         920,7 kB / 976,5 kB
 5. [✓] org.freedesktop.Platform                 24.08          i      flathub         184,4 MB / 261,3 MB
 6. [\] com.skype.Client                         stable         i      flathub         192,5 MB / 193,1 MB

Why so much? Please note that I normally don't use Flatpak unless absolutely necessary.