Google Android Pixel April 2020 Security Update to bring an expected “eyes open” requirement for pixel 4’s face unlock. Earlier Pixel 4’s face unlock has serious issues; it used to unlock the device even if your eyes were closed.
Google received massive criticism for its faulty Face unlock when pixel 4 was launched. Apple’s Face ID has been nearly flawless and the best face unlock system since the 2017 iPhone x launch.
There are a few other fixes, which you can see below in the screenshot. It mentions a fix for dropped Bluetooth audio, occasional lag, etc.