EV used cars are basically dead batteries. It makes a lot of sense to see used EVs price plummet. The index being used to make this comparison doesn't seem to disclose the car category, so it's hard to draw any conclusions.
If tesla car specifically drops in value, compared to other electric car brands for similar vintage/model vehicles, then you can draw a conclusion. Otherwise, it'd be merely confirmation bias.
Source please.
Not sure where I read that (I think it was some dude's Tweet), but it seems relevant here.