Bug fixes include probabilistic display error issues when playing videos and probabilistic flicker issue. The update lets you turn off the flashlight feature while screen-off with a short press of the power button.
The system performance and stability are optimized to give a smooth experience. The company is rolling out the update to Realme 6 phones in a staged manner. So, expect a wider roll out in the coming days. You can check it manually by going to Settings -> System update.

Realme 6 update changelog:

[Security]

Updated Android security patch: Dec, 2020

[Settings]

Added short-press the power button to turn off flashlight feature while screen-off

[Camera]

Fixed the probabilistic display error issue when playing videos

Optimized system performance and improved system stability Fixed the probabilistic flicker issue Realme 6 is getting a new update with December 2020 security patch  optimizations  and bug fixes - 34