Google Pixel owners in Canada receiving Preview update with new feature
The letter "P" in the build number indicates it as a Preview build, which isn't supposed to be spread over-the-air Perhaps its emergence is an error on Google's part. Nevertheless, the update does add a new feature which isn't mentioned in the change log. It lets users double-tap the screen or lift their device to check notifications without turning on the entire display.
It's not known whether this update will make it out of Canada, and whether it was supposed to be released in Preview form in the first place. However, users report that the new feature works without bugs and obstructions. So whatever the case with this update it is, at least it behaves as a finished piece of firmware.