Google Pixel community manager Orrin has confirmed that Google has officially acknowledged issues with lock screen swiping on devices running the latest version of Android, and is actively investigating. The Android 8.1 (Oreo) update has thus far been mostly limited to devices in the Nexus and Pixel range, from the Nexus 6 onward. Reports of the problem on custom ROMs from other devices are scattered. The Nexus 5 is a bit of an outlier, with a custom and unofficial version of Android 8.1 available. There are no reports of the issue from Nexus 5 owners thus far, though this may simply be due to the small number of users, and the fact that many of them, if they experience such an issue, may chalk it up to the device's older processor. In any case, with Google on the issue, Orrin stated that he will be reaching out to users reporting the problem in order to obtain log files in order to help Google diagnose and fix the issue.
The issue in question seems to be exclusive to Android 8.1, with users on the slightly older Android 8.0 (Oreo) not reporting any problems. For the uninitiated, the problem here is that swiping on the lock screen does not seem to work like it should. Many users, mostly Pixel 2 and Pixel 2 XL users, are reporting that they have a hard time swiping up to unlock their device, or swiping down to bring down the notification and quick settings menus while on the lock screen. Once the device is unlocked, however, the problem seems to vanish without a trace, leaving all functionality on the device outside of the lock screen perfectly smooth.
Some users have theorized that the problem lies with code meant to reduce accidental actions while the phone is in a user's pocket, potentially pressed against their skin with only a thin patch of fabric as insulation. In this condition, the touch screen and fingerprint reader can both still work, leading to accidental touches and actions. If this is the case, Google's fix may be as simple as disabling this code, which may mean that more users will begin seeing accidental touches and swipes with their phones in their pockets.