2019 Civic turned off on Motorway

I am looking for any ideas about what could have happened today when I was driving and my car shut off on a motorway. I have a 2019, automatic turbo Honda Civic.

I was going at 70mph, with lcas and dynamic cruise control on. I went to change lane, and it felt like as soon as I turned the wheel after indicating, my car shut off. My dash went black with the white "insert key" icon (not sure what this is actually called).

I lost power steering and the car immediately began slowing down. I tried to turn the key and don't believe I could, but in my panic it's possible I didn't fully try to rotate the key incase I screwed up the engine if I tried to turn everything back on while the car was at speed. This may have been the wrong intuition, but again I am unsure if i was able to turn the key anyway.

I flipped my hazards on and got over to the left lane. This was a smart motorway so I had no hard shoulder to get into, hence why I was so panicked. I luckily had enough of a gap behind and people were moving over. Once the car came to a stop I essentially restarted the car by turning the key back to fully shut the car off and forward again. It came back to life and I pulled away.

I don't remember touching any part of the key side of the wheel when turning or indicating. I was wondering if it was possible I had left the key in only half turned? And perhaps it slipped back, but it felt like it was in the driving position when I tried to turn it when it first shut off.

Any information or suggestions would be greatly appreciated. I want to try and work out what could have caused this before getting on a motorway again.