While not a huge deal, it seems that the GameObject menu items got reordered for some reason, most notably that “3D Object” and “UI” are now at the bottom of the list:
I’ve tried to restore the original layout, but that doesn’t change anything. Is the ordering something that users have some control over? Or has this always been unstable/random, and I’ve just never noticed? This is on the latest 2021 LTS release.
I would suspect some editor script (asset) messes with the order by adding something to those menu items but giving them a different priority. I believe the menu item system either gives the last added menu item or the one with the highest priority precedence.
If you open Preferences → Diagnostics, and in the Editor foldout there’s a checkbox for MenuDisplayPriority. Once you restart the editor, you will see the priority of each item on the create and other menus. You can use this to see what’s putting it at the bottom.