New Safety feature on Caddillac XT5 400?

I have a 2021 Cadillac XT5 400. fully loaded. Bought new Clearwater Florida Dealer. Nice car good handling decent acceleration. Great cabin amenities and what I thought were tolerable autonomous driving features.

While driving up a steep incline today I had to slow to a stop and retrace my path a few yards. I eased off the throttle and allowed the car to creep backwards using the brake pedal to slow my backward motion back down the incline.

The vehicle decided it was not only a good time to save gas and kill the engine but also when I applied the gas to resume my forward motion it also had shifted into neutral!

So no engine, no drive and no power brakes? No Sh!?
Has anyone else experienced this as well? What is the factory excuse for such engineering? Or...is there a problem with my vehicle?. I am sure the factory excuse is "Driver error". I should have shifted in to reverse.... yeah might as well try that next time...?!!!