Sensor light

If you can see the light with your naked eye, not a camera, it would indicate that the sensor is producing infrared light at a slightly different wavelength. It does not indicate a problem with either device.

Exactly what isn’t working?

Yes, I understand it is the proximity sensor, but what is not working? Are you suggesting the sensor does not darken the screen when you put it near your face?

Yes, it is normal. The “light” is actually infrared, meaning we humans would not normally see it. However, it can sometimes be seen by digital cameras.

Face ID is not related to the proximity sensor.

You are quite welcome.