OnePlus recently published two big updates of Oxygen OS to 5.1.6 and 5.1.8 versions. These updates were released for OnePlus 3, OnePlus 3T, OnePlus 5, OnePlus 5T and the newest OnePlus 6 which was released couple weeks ago. Main reason why OnePlus published update so fast after premiere of its new device was problem with bootloader which allowed for installing modified system files without root. Although update solved this problem it looks that it caused other issue.
On forum of OnePlus company we can find many complaints about problem with unexpected battery drain of OnePlus 6. People suddenly noticed that after update of OxygenOS to 5.1.8 version battery in phone runs out very quickly, and also some people informed about problem with shutting down of their device even when phone capacity of battery is around 50%. Second problem can be solved easily, because all you need to do is to plug your device and then phone can be turned on once again, but we can't solve first issue on our own. Problem with battery is connected mainly with OnePlus 6, but some posts were added by owners of OnePlus 3T. We hope that OnePlus will release another update rapidly.