How to activate the ambient light sensor on the X1 Yoga Gen 5?

I recently bought an X1 Yoga Gen 5, but I can’t seem to find the ambient light sensor, which it definitely has according the specifications document The advice from the clightd wiki doesn’t work unfortunately.

Can you help me activate this sensor?

You might need the iio-sensor-proxy package installed …

It is installed and the rotation sensor is recognized

Any other ideas? Maybe it is missing in the kernel?

So the iio-sensor-proxy.service is enabled ?
Maybe you also need either AUR (en) - clight or AUR (en) - wluma

Some hints are provided here Backlight - ArchWiki