Mechanics of terminating leases before D check are a separate issue from this.
The issue is that for years and years, the auto-renewal price was based on the current lease price. Sometimes in the recent past, this was changed, and auto-renewal (and manual renewal as well) is based on default (recommended) price, causing lease prices to jump, sometimes astronomically.
An aircraft that is not popular is often listed on UM at minimum, 50% off. If an airline leases it for 1 year, at the end of 1 year, the price is going to jump 100% on lease renewal.
I think the old functionality should be restored. Or, if the current functionality stays, the system should have a big red warning: "On lease expiration, the lease price will increase x%".