As of the writing, there is no official statement from Facebook regarding the reason for changing the icon to black and blue. However, it may be related to the upcoming full release of iOS 18 on ...

"It's a feature on the iOS 18 beta. You can make your background dark plus your icons either light, dark, or tinted (based on the color of your background or whatever color you want)," said one reply.

That left my Facebook icon with the dark background after the app update. My phone was not in dark mode. The iOS update to 17.6.1 also was available for my phone, which I also installed.

That left my Facebook icon with the dark background after the app update. My phone was not in dark mode. The iOS update to 17.6.1 also was available for my phone, which I also installed.

You might be wondering why Facebook's icon suddenly turned black last time. It might be a bug or just a gimmick, but who knows what this is all about.