It's normal for the fan to stay on after parking your EV in hot weather. The car's cooling system is trying to regulate the temperature of the battery and other components. It's a safety measure. But if the fan runs for longer than an hour or you hear any strange sounds it's a good idea to get it checked out. Otherwise, it's probably just the car's cooling system working as intended. Just make sure it eventually shuts off.
I’m dealing with the same annoying thing. The fan just keeps running for like 15-20 mins after I shut the car off, and it's sucking up about 5% of the battery each time. At this rate, I’m gonna be dropping serious cash just to charge it up for that dang fan to run!