Did those owners pay their protection money don't light my house on fire subscription fee? /s
Apparently it has to do with the starter. From the article:
According to BMW, water can enter specific areas of the starter in the affected vehicles, causing corrosion. This could result in the engine failing to start.
In some cases, a short circuit could occur, leading to local overheating in the starter. "In the worst-case scenario, this could potentially result in a vehicle fire," the company warned.