Google has been hard at work to give many of its apps (and Android itself) a dark mode – much to the universal joy of people annoyed by the company's move towards a more generous use of white space. Google Photos had one of the buggiest implementations of the new theme, as it only surfaced with a half-black, half-white interface on Android Q in the beginning and didn't even have a toggle to turn it on or off inside the app. By now, its UI problems are fixed, and thus, dark mode appears to be rolling out wider. It shows up for users on Android Pie and Oreo with their own system dark themes enabled.
To test if your Android-Pie-equipped phone received the new theme, head to Settings -> Display -> Advanced -> Device theme and turn on the limited dark mode. You can also automatically switch themes if you pick a dim wallpaper – which is what you have to do if you're on Oreo since it doesn't support manually selecting color schemes.
If you're lucky, Google Photos should respect this setting and switch off its lights. Since this is a server-side change, you might have to wait a while until the app does that for you – though using the latest version of the app could help. Toggling on dark mode in another Google product, such as Messages, might trigger it for Photos, too. The apps are all somehow connected.
Google Photos doesn't have a toggle of its own to enter dark mode independently of system settings, yet, though. So, if you're running a lower version of Android, that means you're left out of the alternative theme club for now, unfortunately.
- Rodrigo Alexandre Sigoli and Edo