If it's a Welcome Back Light, it's supposed to come on when the switch under the entry door closes, providing a ground signal to the control module. If you can locate the module, you could interrupt one of the module wires to disable it.
If under warranty, next time you take it to the dealer for service, you might put it on the punch list. It's likely the control module - maybe the switch under the door.
I've attached 2 files that may help if you want to try to modify the circuit yourself. One shows the location on a Landmark 365. The other is a block wiring diagram. You may have to take down the rear wall of the pass through basement storage to locate the module. If you do modify the circuit, you might want to interrupt one of the wires with a switch so function can be restored in the future.
Note that the block diagram is based on the Landmark implementation, which includes a control panel switch for the aisle light. If you don't have a switch, your implementation will be a bit different.