NSToolbar items don’t react to Dark Mode changes in apps compiled with macOS 15 SDK:
My app was installed as a notarized app on a Tahoe VM with the same build as distributed in the App Store, based on macOS 15 SDK. When toggling Dark Mode, toolbar items are not updated, but only after opening a new window / tab or e.g. customizing the toolbar.
The app is using default methods for the toolbar, defined in its corresponding XIB file, and working in previous macOS versions. This issue could be confirmed with various apps built with an SDK prior to macOS 26 "Tahoe", e.g. Apple's Clipboard Viewer.
Reported via Feedback Assistent (FB19107572).