You’re blowing out all of the water that’s accumulated in your exhaust system from starting the engine and not actually DRIVING the car long enough to heat up and evaporate all of the accumulated moisture.
That’s one of the reasons why daily drivers that only go a couple of miles to and from each trip will need an exhaust system every few years.
The water rots the exhaust system from the inside.
You need to get the exhaust system hot enough to evaporate ALL of the moisture produced during the engine warm up period, otherwise it sits there and rots everything.