2025 Hyundai IONIQ 5 N-Line S RWD / 2016 Suzuki Vitara 1.6L Petrol AWD
Some (non-merc) ex-police cars in the UK had a switch fitted to stop the internal lights from coming on when the doors open.... in addition to the original rocker/slider switch.
If it's an ex-limo, maybe is switches-on the lights at the back?
If it's hidden from sight, could it be some sort of an aftermarket immobiliser or alarm?