OnePlus 8 is getting a new OxygenOS update from T-Mobile. Unfortunately, the latest update is still based on Android 10. This new update for OnePlus 8 comes with software version 10.5.23.IN55CB and weighs 182MB in size.
The update brings November 2020 security patch, improved call performance, and some general fixes and improvements. You can check for the update manually by heading to Settings -> System -> System update -> Check for update.
It’s worth mentioning that OnePlus has already released the Android 11 update to the global variant of the OnePlus 8 series smartphones. But, T-Mobile’s OnePlus 8 is still in the queue for the Android 11 update.[source]