It’s still an incandescent, unfortunately. If they changed it to an LED, it might be bright enough to be useful.
'The small light bulb was replaced by a LED diode, but the intensity of the tired firefly remained'
https://www.hodinky-365.com/blog/casio-f-91w-review
I wear F-91W every day and FWIW, the light is adequate to see time at night.