It's an EV - all EVs were over-priced but many have dropped in price to more realistic levels - nothing to do with being a Honda.

Absolutely correct, Even some unfashionable ICE cars doing better than that.

A vehicle I've never even heard of. Unfortunately its an EV, but at least you are only renting it.

If you want an EV buy a Dacia Spring with £6k off its £16k price tag after just 11 miles use.

Pre reg models of that vehicle available with 8k off list is an indication that they are not popular.

This just proves that the car was overpriced when new (so are many others), so market forces are finding a more realistic value on the 2nd hand market.

Brand new ones available on Autotrader with as much as £8k off rrp.

I love the car but no more Honda’s for me after this,

As has been said, the extreme depreciation has little if anything to do with it being a Honda, so a knee-jerk reaction like this isn't going to help you avoid being in the same situation in future.

What would help is doing some research (before signing on the dotted line) into the pros and cons of the actual vehicle you are looking at (Honda e:Ny1), the general type (EV), along with whether or not a PCP is the best option.

I remember back in the 90's being told that something like a Ford Scorpio would lose £10k off its value as soon as it was driven out of the showroom. And that would have had a rrp of maybe £25-30k

How much it's worth is irrelevant if it's on PCP. The cost to you is the deposit you paid and the sum of all the rental payments.

If a salesman told you that you would have equity in it at the end, you won't with any car from any manufacturer. They will say you do if you trade it in for a new car from them, but it has no actual value in the market.

In fact, if it's already worth less than the balloon payment, it's Honda losing out, not.you.