Tap to wake not working on your Pixel? Blame Android 16
The issue is not widespread, though

Google pushed out the stable Android 16 update for its Pixel phones on June 10. Since then, there have been sporadic reports of users running into issues with the back gesture and the 3-button navigation bar acting glitchy. There now seems to be another annoying bug in Android 16 that seems to have slipped through Google's testing, one that makes unlocking Pixels a tad frustrating.