Android dark mode issues seem restored, but we can help iOS users still (not) in the dark.
*Update: Well, with some annoyances, we have been able to figure out how to re-enable Facebook dark mode in the iPhone app. Facebook has confirmed that Android users should also solve their problems now. This is the iOS fix:
First, uninstall Facebook, and then reinstall the app.
If Dark Mode is not available, please force quit the app by sliding your finger up from the bottom of the home screen slightly, and then swipe up on the Facebook app.
Next, go to the iPhone’s settings and scroll down to the “Apps” section. There, choose Facebook. In the Facebook application settings, turn on “Upload HD Video” and “Upload HD Photos”. Indeed, this allowed us to restore Facebook dark mode on at least three different iPhones.
We tried to restore Facebook dark mode by clearing the app cache and storage on some Android devices, but unfortunately, this does not seem to work, but it seems that these issues may be being resolved now.
As users complained online that the brightness that Facebook’s normal mode could not bear was beyond their capacity, the Facebook dark mode disappeared without warning on iOS and Android.
Some users believe that several accessibility options, including “dark mode”, seem to be missing after the update. According to data from the Apple App Store, we are running version 319.0.0.38.119 (292363515) on iOS. The latest update time of this version is six days ago, and there is no problem with dark mode.
We can confirm that the problem seems to be bothering version 320.0.0.36.122 (293873823) and earlier version 319 of the application. We have downloaded the new iOS version on multiple iPhones and were able to replicate the problem.
Strangely, this is not the first time that Android users in early May reported a similar situation, but it could be corrected without confirmation or warning from Facebook. However, it is clear that the last power outage on May 26 was even more widespread-our article on how to enable Facebook Dark mode suddenly increased traffic, which clearly indicates that the problem occurred suddenly and without warning.
Now, some users report that Facebook dark mode is reappearing, as suddenly as it disappeared on May 26, which indicates that this is a server-side adjustment and the above fix can be triggered faster-we certainly can’t delete it again. Follow Enter dark mode with the same steps.
Facebook has confirmed to our sister site Tom’s Guide that it has resolved the issue on the Android app, which means that Android users should reactivate dark mode in the near future if they have not used it yet:
“We have restored service for those who experienced a technical issue that caused some people to have trouble accessing certain features on Facebook’s Android app,” the spokesperson told Tom’s Guide.
What happened to Facebook Dark Mode setting?
The question of what happened is weird-first of all, Facebook seems to ignore the fact that iPhone users are experiencing this problem completely, focusing only on the (currently unsolvable) Android Facebook dark mode problem.
A Facebook company spokesperson acknowledged this problem in a statement to us: “We’re aware that some people are having trouble accessing certain features on Facebook’s Android app. We’re working to get things back to normal as quickly as possible.” But this does not explain the iOS application, but fortunately, there seems to be at least a way to restore it to the iPhone and iPad.
Our guess is that by switching the settings in iOS, you will force the app to reset its cache and re-enable the mode for some reason it cannot explain why the same manual app cache clearing operation on Android cannot be performed in the same way to work.
This is obviously a bug because Facebook is unlikely to want to remove the dark mode, but it will obviously affect and trouble thousands of users.
How to enable Facebook dark mode
If you’re fresh to these issues and want to see if you can add dark mode, it’s a simple process (if the option is there for you).
To enable dark mode on a mobile app, click the menu icon in the upper right corner of the app (for Android) or click the three lines in the lower right corner (for iPhone), and select “Settings and Privacy” (represented by a cog icon).
Here, you will see the “Dark Mode” option (with the moon icon). Click this button, you will see three options: turn on, turn off and use system settings.
The first two are self-explanatory, and the third will use whatever color scheme you choose for your phone’s operating system.
Thanks for reading until the end.
Jason 
Tech Elucidations