Created attachment 194091 [details] Application window without menu There is a widget in KDE to move the main menu from the application window to the panel, if the application has the current focus. In that way, the application window has no main menu, the KDE panel with the widget take care of that. Using LibreOffice with this configuration, the menu in the application window is not present, as expected, but there no menu in the panel either. As the attached image show, with the flatpak version there's no menu of any kind, but the AppImage version has the expected behavior.
Created attachment 194092 [details] AppImage version with the menu in the panel Including image with other version (Flatpak does not work and AppImage does).
Thanks for the report. This flatpak + wayland issue (you are using Wayland, right?) is already tracked in bug 156387. *** This bug has been marked as a duplicate of bug 156387 ***