Many have reported a memory management issue with the Pixel 3 and 3 XL. The issue caused the device to prematurely shut down apps in order to preserve RAM.
The December security update, which includes more than 13 patches, will improve memory performance, camera capture speed, audio issues when using Android Auto compatibility, contouring HDR colour on certain apps, camera shutter performance and unlocking when using Bluetooth. The update will also adjust the camera’s autofocus behaviour, though the notes don’t explain how.
Some of the other fixes apply only to the Pixel Stand, such as improvements to notification visibility and hotword performance.
The update is rolling out over-the-air now, according to Google. There should be a notification when the patch hits your device, otherwise, it’s available in the smartphone’s ‘Settings’ menu.