From my understanding some AP’s are related to the cars sell on value at the end of the lease. It is why you see some higher spec models showing a cheaper AP than the lower spec ones. It is easier to sell on a higher specification in the second hand market. Rarely do the lower base models make relative money back.
An example of this was the Mercedes A class hybrid being cheaper in Premium plus than Premium. I think the GLA had the same thing. Either way the probability of a car selling at good price on the second had market has a bearing on the AP.
I expect it is why we could see good AP’s on electric cars as they become more and more desirable in the market and keep a good sell on value.