In current Rawhide (Fedora-Rawhide-20210120.n.0), the welcome screen doesn't show when booting Workstation live. Trying to run it from a console shows the apparent problem:
[liveuser@localhost-live ~]$ /usr/share/anaconda/gnome/fedora-welcome
Gjs-Message: 13:07:40.019: JS WARNING: [/usr/share/anaconda/gnome/fedora-welcome 21]: Requiring Gdk but it has 3 versions available; use imports.gi.versions to pick one
Gjs-Message: 13:07:40.066: JS WARNING: [/usr/share/anaconda/gnome/fedora-welcome 25]: Requiring Gtk but it has 3 versions available; use imports.gi.versions to pick one
Gjs-Message: 13:07:40.498: JS WARNING: [/usr/share/anaconda/gnome/fedora-welcome 149]: Too many arguments to function Gtk.init: expected 0, got 2
(fedora-welcome:2890): Gjs-CRITICAL **: 13:07:41.860: JS ERROR: TypeError: Gtk.WindowType is undefined
(fedora-welcome:2890): Gjs-CRITICAL **: 13:07:41.860: JS ERROR: TypeError: welcomeWindow is null
I guess something changed in gjs? Anyway, this is breaking the openQA tests so it's pretty important.
Ah. Problem is it's trying to run against GTK+ 4 now.
This bug appears to have been reported against 'rawhide' during the Fedora 34 development cycle.
Changing version to 34.