2022.9 continues the clean-up and stability work ahead of the forthcoming LTS release, plus introduces the Inspector as a part of the default layout for all new projects (as well as a tweak to the Room Editor layout so it now uses the Inspector rather than the old custom panels). This release also gives you the ability to control your texture groups more precisely in the texture groups editor, so that you can manage in-game loading times and memory usage. It does also have some important changes for creating/loading Game Options, as well as various UI/UX improvements brought about by our recent website change to offer converting your old YoYo/GameMaker Account to a new Opera Account.
On the runtimes side, there is the texture groups change mentioned already, plus 2022.9 adds touch support in Windows games and raises the SDK version supported on a few console platforms - so please do read the runtime release notes carefully, as you may now need to change your setup.
For all changes/fixes since 2022.8.1 see the IDE notes page and the runtime notes page.