https://wccftech.com/pixel-4s-screen-attention-wont-be-ported-to-older-pixel-phones/

OEMs such as Google, Samsung, and OnePlus usually make it a point to port features from their latest flagships over to older devices. For example, the older Pixels recently got the Pixel 4's Astrophotography camera mode, the Galaxy S10 series got support for DeX for Windows/Mac, and older OnePlus devices have received features such as Zen Mode, DC dimming, and more. However, it appears that one of the Pixel 4's lesser-known features won't be making its way to its predecessors. The Pixel 4's screen attention feature keeps the display on as long as you're looking at it. We've seen this implemented (badly) in other Android Forks, and Google seems to be the only people who managed to get this right.

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