Used aircraft pricing by AI brokers is not dependant on the new aircraft pricing. New a/c pricing is dynamic and depends on the number of orders, and in this case is probably lower than standard as it doesn't have that many orders. Used a/c pricing depends on the aircraft specs, and they always start with a relatively high price when they enter the market and the longer the plane is there the lower the price goes gradually. (the price advisor you see is a different thing and it consideres for example the respective new plane price, so in this case the advisor would say those are expensive..)
This has been the system for a very long time, and it hasn't had any changes recently, so not a bug.