Thanks everyone for the helpful replies. I did some more digging and it's definitely one of two auxiliary radiators that I have. From my internet research, most if not all have an auxiliary radiator on the driver side (US Spec), but a smaller subset have a second auxiliary radiator on the passenger side; M Sport and Track package, but perhaps others as well.
To my knowledge, this car did not come with the track package, but it is an M Sport.
The part number is on the side: 17117628057
It seems as though the same part is for either the driver or passenger sides.
These are about $200.00 online and seem to be very easy to replace.
No warranty concerns here.