Since iPadOS 26.1 I notice a new annoying bug when changing the dark mode option of the system. The appearance of the UI changes, but no longer for view controllers which are presented as Popover. For these view controllers the method "traitCollectionDidChange()" is still called (though sometimes with a very large delay), but checking the traitCollection property of the view controller in there does no longer return the correct appearance (which is probably why the visual appearance of the popover doesn't change anymore). So if the dark mode was just switched on, traitCollectionDidChange() is called, but the "traitCollection.userInterfaceStyle" property still tells me that the system is in normal mode.
More concrete, traitCollection.userInterfaceStyle seems to be set correctly only(!) when opening the popover, and while the popover is open, it is never updated anymore when the dark mode changes.
This is also visible in the standard Apps of the iPad, like the Apple Maps App: just tap on the "map" icon at the top right to open the "Map mode" view. While the view is open, change the dark mode. All of the Maps App will change its appearance, with the exception of this "Map mode" view.
Does anyone know an easy workaround? Or do I really need to manually change the colors for all popup view controllers whenever the dark mode changes? Using dynamic UIColors won't help, because these rely on the "userInterfaceStyle" property, and this is no longer correct.
Bugreport: FB20928471