Leaked screenshots show the updated features that will be coming on to the MIUI 9, Xiaomi's own user interface based on Android Oreo. They also happen to have aspects similar to Android-P beta. Therefore, it could be assumed that when the MIUI 10 rolls out, it will also have a lot of these features because it will be based on Android P.
At the Google I/O 2018, we already saw how Android P beta is rolling out on numerous brands and devices, one of them being Xiaomi’s Mi MIX 2S. On the other hand, the MUI 9 v8.5.11 Nightly Build shared by FunkyHuawei.club on XDA Forums is meant for the Mi MIX 2.
Even though the build is currently based on Android Oreo, it provides users with a sneak peek of the new features that will be rolling out in the coming months. The screenshots show how the new MUI build has a notification shade with rounded toggles that turn blue when a certain service is enabled. In fact, the entirety of the user interface (UI) has a more rounded design to it.
Another change is how the volume slider comes in from the side instead of from on top now. The multitasking window also displays the recently opened apps via tabs similar to the Android-P design.
One feature visible on the MIUI 9 build is the 'Clear All' button, something that's lacking in Android P beta.
Once Android P officially rolls out, Xiaomi will probably launch MIUI 10 soon afterwards. It will be out-of-box for smartphones that launching thereafter.