Building xdg-desktop-portal-gnome with GCC 14 fails here:
https://build.opensuse.org/package/live_build_log/openSUSE:Factory:Staging:Gcc7/xdg-desktop-portal-gnome/standard/x86_64

Due to (exhaustive list of errors):

../src/inputcapture.c: In function ‘create_input_capture_dialog’:
../src/inputcapture.c:412:46: error: passing argument 2 of
‘gtk_window_group_add_window’ from incompatible pointer type
[-Wincompatible-pointer-types]
  412 |   gtk_window_group_add_window (window_group, dialog);
      |                                              ^~~~~~
      |                                              |
      |                                              GtkWidget * {aka struct
_GtkWidget *}
In file included from /usr/include/gtk-4.0/gtk/gtk.h:302,
                 from ../src/inputcapturedialog.h:21,
                 from ../src/inputcapture.c:22:
/usr/include/gtk-4.0/gtk/gtkwindowgroup.h:71:70: note: expected ‘GtkWindow *’
{aka ‘struct _GtkWindow *’} but argument is of type ‘GtkWidget *’ {aka ‘struct
_GtkWidget *’}
   71 |                                                  GtkWindow         
*window);
      |                                                 
~~~~~~~~~~~~~~~~~~~~^~~~~~

See the meta bug#1220571 for more info.