The OnePlus 6T has been running Android 10 for a few months now, but not so on T-Mobile. Units bought from the magenta carrier have been stuck on Android 9 Pie, for what seemed like forever. Not anymore, though. The carrier has finally started rolling out the update to Android 10 for its OnePlus 6T units today. As usual, this is a staged affair, so it may take a few days before your TMo 6T pops up that update notification, but it is on the way nevertheless. Once you install the ~1.6GB new software, you will have Android 10 on board, as well as the December 2019 security patch level....
Source: https://www.gsmarena.com/t_mobile_s_oneplus_6t_finally_receives_android_10_update-news-41552.php
