It looks like Gnome session, but it isn’t - how many users downloading the Gnome-spin use a different WM?
It is the Workstation, this is an edition and not a spin.
It is difficult to understand, what do you mean with that?
Gnome can be installed with the everything ISO, which lets you install the Gnome desktop separately.
So we are not able to measure the downloads because as the name implies, you can install everything with it.
If you look closer, gdm runs /usr/bin/gnome-shell --mode=gdm so if that is not a Gnome session, then what is?
Besides, gdm is a Display Manager and not a Window Manager, and Display Manager is kind of an obsolete term as it doesn’t manage displays like display managers used to do may years ago.
Gnome, session, WM, (G)DM, spin - you’re mixing in quite a few terms here.
If you’re asking about Fedora’s default/standard/main/you name it edition (LDE folks will kill me for either term), that is about Fedora Workstation which comes with GDM as DM and Gnome as DE and mutter as WM:
Being default means it’s a good base even if you install and use - say - Sway, in the sense that you can easily test on “default” if something breaks, to make sure it’s not your “non-default” DE. It’s not a good base if you strive for minimal, of course.