The Pixel 4’s face unlock now has that vital security feature it was missing at launch>
Android Central – Joe Maring
On April 6, Google began rolling out the April 2020 security patch to Pixel phones. It’s been discovered that this patch includes a “require eyes to be open” toggle for the Pixel 4’s face unlock. This is something that’s been missing since launch and makes face unlock much more secure.
Link: https://www.androidcentral.com/pixel-4s-face-unlock-now-has-vital-security-feature-it-was-missing-launch