'Not a bug, but a feature': Windows Hello face unlock doesn't work in low light

Windows Hello is Microsoft's security mechanism on compatible Windows PCs that allows users to authenticate with biometrics such as facial/iris recognition, fingerprints, or PINs to access their accounts. Overall, Windows Hello is a great security feature, but that doesn't mean it doesn't have its limitations. For example, it seems that Microsoft recently changed the way its face unlock feature works, which has received a lot of negative feedback from the user community.

Windows Hello has not been working as expected since at least April's Patch Tuesday update, as discovered by Windows Central. Specifically, the facial authentication mechanism on Windows Hello will now require an infrared (IR) sensor and a color webcam to work properly. Previously, Windows Hello relied solely on the IR sensor to create a 3D facial map, similar to the iPhone.

IR sensors work great in low light, but Microsoft no longer allows users to rely solely on them due to a security patch. It's important to note that most webcams don't illuminate the environment themselves, relying on external light. This means that Windows Hello simply won't work in low light for many users.

In real-world testing, Windows Hello still works under warm yellow light (as shown below):

However, this feature currently does not work in darker environments, such as dim red lighting (as shown below):

However, it seems that Microsoft has not implemented this change completely. Users have reported that if they disable the webcam via Device Manager, Windows Hello will revert back to using just the IR sensor and continue to work as before. While this may be a temporary solution for current users, it would be interesting to see if Microsoft also patches this 'loophole' in the future.