I believe the BSM sensors are in the back of the rear fenders, thus should not interfere with a bike rack. However, the parking assist sensors can be affected.
That’s the Rear Parking SONAR. It uses ultrasonic sensors facing straight back from the rear bumper and allows you to get within close proximity while parallel parking.
I have a 21 Nightshade so I can’t speak from experience on BSM/RCTA. But I do have the Rear Parking SONAR and I have to disable it through the driver cluster screen to prevent the “freaking out”.
BSM - Blind Spot Monitoring is to prevent changing lanes into someone who is in your blind spot. So, the RADAR sensors are looking at the vehicle’s rear side. I wouldn’t expect the bike rack to have any effect while in up right “not in use” position. I do think you may have an issue while the rack is in use with bike(s) due to the width and positioning in “view” of the sensors.
RCTA - Rear Cross Traffic Alert helps prevent reversing into the way of traffic that is traveling perpendicular. Think backing out of driveway onto a busy street. This uses the same RADAR sensors used by BSM. So, same potential conclusions as BSM?
I recommend going back to the dealer with your rack and a bike. Disable Rear Parking Sonar but leave BSM/RCTA on and see what happens when you go in reverse.