I thought it was very strange there was no config.xml in the zip file. Was this intentional?

Portable users often complained that unzipping the new portable overtop the existing portable directory would then overwrite their config.xml with all their settings, so they would lose their settings. By not including a config.xml in the zipfile (which isn’t needed, anyway), unzipping the portable no longer deletes their existing settings, and this is deemed A Very Good Thing.

Previous updates always included config.xml in the zip file which I compare with the installed version to see if anything needs to be cherry-picked.

Notepad++ always has the full template for config.xml compiled into the source code, and if any element of config.xml is missing, it will automatically populate it once N++ tries to write the config file (upon exit). So you’ll never be “missing” anything in the GUI preferences dialog.

But you’re right, you might not notice that a new setting was added. The change.log will sometimes explicitly mention new preference-dialog settings; and, even if it doesn’t, the User Manual tries to update the Preferences documentation, usually sometime between the Release Candidate announcement and the official release of the new version – and almost always before a version has been triggered for auto-update. (There weren’t any new preferences in v8.9.4, but there was one in v8.9.3, and you can find it by “find in page” for 8.9.3 in your browser on that page.)