Looks like the Android 8.1 update brought along a new issue with it. Over at the official Google Pixel community, a lot of users have been complaining about slower screen wakeup response for more than a week now.
Specifically, users – majority of whom are Pixel 2 XL users – are complaining that post the update, whenever they try unlocking their device through the fingerprint scanner, the device’s screen wakes up after a significant delay.
Some say they observe the same behavior on pressing the power button as well. Turning on the ‘always on display’ seems to have fixed the problem…