The October 2020 update focuses on a security flaw in Android’s System component that could allow an intruder to gain extra permissions through a “specially crafted transmission.” Others allow running arbitrary code, possible data leaking through the media framework, and the possibility of rogue apps getting extra permissions by bypassing user interaction requirements. All but one of the flaws are still considered “high” severity, so you’ll want to upgrade as quickly as possible.
It also includes some fixes for lingering Pixel phone problems. The 4a now has improved auto-brightness response in specific lighting conditions, and should be more responsive when you’re using a screen protector.
Read more: Pixel 5 vs older Google phones
All currently supported Pixel phones (from the 2 onward) get a series of common fixes. The October 2020 Android update fixes a problem with some devices getting stuck in the boot process, and prevents call notifications from inadvertently turning off. You’ll see fixes for undetected overview swipe gestures in the launcher and a missing auto-rotate icon in some orientations. Every phone expect for the Pixel 2 family also gets better auto-rotation in specific orientations.
Not surprisingly, there are no updates for the Pixel 4a 5G or Pixel 5 when they haven’t been released yet.