Not being the best on the update track record, Asus has been trying to improve itself with the last year's ZenFone 6 series. The device already got an update to Android 10 last month, and now, the company is mounting an incremental build with new features and security improvements.
To start with, the new firmware update introduces March 2020 Android security patch level to the ZenFone 6. Since its already April, a month delay is something quite acceptable from the Asus. Moreover, this update will be of great help to Indian Reliance Jio network users, since this update will enable the VoWifi feature in their Asus 6z. Along with Indian users, Tele 2 customers in Sweden are also getting support for VoLTE with this firmware patch.
The update also carries the usual set of expected bug fixes and improvements in the system. The fact that this update is just an additive update gets strengthen by its size. This update is slowly rolling out to Indian, European and Global units in stages and you might need to wait a little longer than other people. So, be patient and wait until your Asus ZenFone 6 gets examined with an OTA notification. Meanwhile, If you are not a person who holds patience, you can try to force check the update via Settings>> System Menu.