Just discovered, during a power-cut, that the keyboard backlights on a Latitude 7390 and also on a Thinkpad Yoga 12 flicker! It can be seen using a high shutter-speed on a phone's camera on "manual", and happens on the first keyboard brightness level and not on the second/higher, probably coz pwm is used for brightness-control. Not sure yet how much of a problem this causes but it would be interesting to know of others experience with this.