Steps to reproduce:
Result: if the appearance is switched from Dark to Light or from Light to Dark after the app is opened, the colors become confused. (40s)

Tested with WPiOS 13.2-beta1 (TestFlight) on iPhone 6S iOS 13.1 Beta 1 in Dark & Light Modes.
The view controller needs to listen for the notification that the mode has changed and refresh the UI.
h/t @rachelmcr for the original report at p5T066-Zv-p2#comment-3427 and @jkmassel for the tip.
I tested this again as part of 13.4 beta testing and found that if you toggle dark mode while the screen is visible the text color still doesn't update for the login/signup, log in, and logged in as screens.
Steps to reproduce:
Result: the buttons become unreadable with dark text on a dark background or light text on a light background if you toggle dark mode for the login/signup, log in, and logged in as screens screens while the app is open.
Tested with WPiOS 13.4.0.1 (TestFlight) on iPhone 6S iOS 13.2.
Result: the icons at the bottom of the post become very light gray on white and are hard to see.
(Left) After switching from dark to light while the app is open and (right) after closing and reopening the app while in light mode, tested with WP Internal 13.5.20191021 (HockeyApp) on iPhone 6S iOS 13.2.
I tested with WP Internal 13.6.20111104 and I can still see the problem happening where switching from dark to light mode, or vice versa, causes some buttons to become unreadable. (13s)

Tested with WP Internal 13.6.20111104 (HockeyApp version) on iPhone 6S iOS 13.2.
@danielebogo do you think you could fix this for the 13.6 or 13.7 release?
@designsimply this is basically the main task for Dark Mode V2. There's a list of elements you can see in the project card that have the same problem. Probably some can be addressed in 13.7? @frosty
Possibly related: https://github.com/wordpress-mobile/WordPress-iOS/issues/13364.
Reader comment text color doesn't update when you switch between dark and light mode, rendering the text invisible against the background. This is visible both in the Reader tab and when accessing all comments on a post through the Notifications tab.
Tested with WPiOS 14.1.0.20200131 on iPhone XS, iOS 13.3.
There was another report of this issue in 2744797-zen, the user notes that the input fields in the post editor were black on black after switching between modes.
They weren't able to grab a screenshot (and I can't replicate as I have an older iOS device that doesn't support dark mode).
I'm closing this as these issues have either been fixed or are tracked on other issues. Since Dark Mode is no longer a project, I think it'd be best to create separate issues going forward so they can be addressed individually.
Recap:
develop (i.e. release 14.5)
Most helpful comment
I'm closing this as these issues have either been fixed or are tracked on other issues. Since Dark Mode is no longer a project, I think it'd be best to create separate issues going forward so they can be addressed individually.
Recap:
develop(i.e. release 14.5)