https://wccftech.com/oneplus-6-face-unlock-can-be-tricked-by-a-photograph/

Contrary to popular belief, the iPhone X wasn’t the first device to come with face unlock. Android has had a face unlock feature for years; it’s just that it wasn’t even remotely good and failed under most conditions. One of the most pressing concerns with the feature was it’s inability to distinguish a photograph from a face, thereby putting the device at risk. Later, it was found out that a photograph could indeed be used to unlock a device. Shortly after, Google added a “liveness test” to face unlock, which required the user to blink. But, like its predecessor, it could be beaten by a video or a gif of the face blinking.

After the iPhone X, other OEMs followed suit to implement their own flavour of face unlock, one of which was OnePlus. The feature made its debut on the OnePlus 5T and ran into some trouble later as it was found to be infringing on some patents. It was then backported to older devices and is now found across all OnePlus devices. Credit where it’s due, the face unlock on the OnePlus 6 is snappy and better than most competition, but it isn’t without flaws, as demonstrated by the following Tweet: