It was a domino effect. When a car with a cold battery tried to charge, it had to wait for the heaters to get it up to a working temperature. This meant a 20 minute charge became 20 (initial) + 10 (heating time) + 10 (replacing extra power lost to heating). A 20 minute charge then takes 40+ minutes. The next car has the same issue. Once this happens a few times, even cars that were warm have cooled down, while queueing.

It’s the EV equivalent of the petrol panics that happen to ICE cars. They idle in the queue until they run out of fuel. It’s an infrastructure problem combined with people learning the limits of a new technology.