It wouldn't surprise me if the biggest factor was just interest rates.
EVs still do tend to cost more than ICE vehicles, and the used market is still pretty new for EVs.
Autotrader is mostly a used car marketplace. So it doesn't really surprise me that after a year where used cars cost more than news ones, and new cars were flipped for immediat profit.
Now that is starting to settle down and people who still can afford a new car just gets it right from a dealership.