I just learned that my ICE vehicle can drain the 12v battery overnight if it fails to turn off the accessories circuit. No lights or infotainment etc. were left on. In my case, it was the switch on the park gear flaked out. I imagine a variety of similar faults could cause the same issue in an EV.

Reminds me of renting a zipcar for a few days and parking it in an underground parking lot.

When I went to use the car after a couple days, the battery was drained. This happened on multiple occasions with different vehicles parked in the same garage.

My best guess is Zipcar has cellular comms to phone home, which enter some weird “always trying to connect” state when cut off from cellular signal underground.

Zipcar’s response was to ban me from renting on their platform ever again for too many disabled vehicles.

My car (a hybrid) has a long-standing bug in the radio system that can make it "freeze" and stay on forever. Only way out once it's frozen is to pull the right fuse (or wait for it to drain your battery all the way).