Kind of sounded like when your try to start an old carbureted car that has not run in a long time trying to kick over. After googling it , I was sent to an Audi forum I was reading this happens to warm the car up faster in cold conditions. And the sound is the secondary air pump sucking in extra air during a cold start to warm up faster. Do our cars do that? This is the first time it’s ever done it and I know I’ve started it on colder days. But after the initial weird sucking/ choking at start up sound it ran just fine.