It's weird because that is the only key that has anything lube/grease on it.
Yeah, it is weird. but I guess EK Brian just likes to lube the Ctrl's. I think there was some complaint about that key squeaking or something. I dunno. Well, tbh, idc. Both my RF's from EK Brian came with lubed L Ctrl's. I just didn't make a big deal about it.
@OP, you were just looking for the LED? lol. There is not one there. That's the goofiest part of the L Ctrl. It has that window, but not an LED. But it gets lubed. So many mysteries in this universe, I have so many questions for G*d when I die.