By now it is probably no longer news to many: GNOME Shell moved from GJS’ own custom imports system to standard JavaScript modules (ESM).
Extensions that target older GNOME versions will not work in GNOME 45. Likewise, extensions that are adapted to work with GNOME 45 will not work in older versions.
You can still support more than one GNOME version, but you will have to upload different versions to extensions.gnome.org for pre- and post-45 support.
Please file bugs with your favorite extensions or have a friendly conversation with your extension writers so that we can help minimize the impact of this change. Ideally, you could help with the port and provide a pull or merge request to help maintainers.
I am all for hating in GNOME for constantly breaking things. In this case though, are they not moving away from their non-standard system to the JavaScript standard? That seems like something to be supported and, in the long run, it will likely lead to less breakage.
Or am I misunderstanding?
Yes but it would have been nicer to have a transition period in which both methods are supported for a little while so that you don’t literally break every extension in existence up to this release
I find it naive to think GNOME would suddenly start caring about compatibility as moving to a standard doesn’t guarantee such.