Hmmm you're right again, maybe I was too quick to cut the connector off.
You see, I bought the car second hand, and there was a huge mess in the trunk.
So I cut off all the wires which had an empty connector dangling by itself. I thought that if the connector is not connected to anything, it must not be important.
I've retraced all the wires, removed all the extra wires going to the fusebox and relays for the components that I don't have, such as stock audio, air compressor etc.
This helped me organize the wiring and fix a bunch of electrical issues.
But maybe I was too quick with this connector.
When I bought the car, it didn't have the air suspension module. So I cut it off lol, the connector.

Now if the connector wasn't connected to the module, I guess there would be no signal going from the ride height sensor on the rear right side to the headlights.

My headlights do have a bunch of errors in bmwscanner which I planned to address once I finished with the other issues.
I'm gonna double check the error and maybe add the air suspension module and re-create the wiring from ride height sensors to the module.

Now if I'm going to take off the inner fender again and break those dumb plastic rivets, I gotta buy extra wide flares for the arches!
Just gotta find the ones that fit with the running boards.