With the Pixel 4 finally shipping to users and reaching more and more hands, we're starting to get wind of a few quirks we didn't expect. Due to the new Soli radar chip, some features you may have grown accustomed to might behave differently, like lockscreen notifications being hidden and the Always-on display automatically turning off after about 30 seconds.
This new discovery comes to us courtesy of Artem who has been putting his Pixel 4 XL through its paces. He noticed that the ambient display would show up for him then time out, even with his phone sitting on a desk. On previous Pixels, the ambient display only turns off in certain conditions to preserve battery, like if the proximity sensor is covered in a pocket.
The difference here is that the Pixel 4 can use its radar to detect nearby movement and thus only activate the always-on display when someone is around. That might save you a few tiny drops of battery juice, but if you prefer to disable the setting and always see the always-on display, you have to change one setting.
Head over to Settings -> Display -> Lock screen display and make sure Always on is enabled, while Show display when nearby is disabled. The latter is what you need in order to avoid the ambient display timing out after a few seconds of inactivity nearby.