I do not know if it is a bug or by design, but here i go:

In the planet screen the total cost for an improvement (upgrade) is shown while the actual cost is the difference between the total cost of the upgraded improvement and the improvement it upgrades from.

Furthermore there are various inconsistencies with the shown number of turns/costs.

In the screenshots i show the upgrade from the "Fertility Center" to the "Replication Center".

First with the "Fertility Center" tile selected, the "Replication Center" in the "Available Projects" list shows a cost of 239 and 2 turns to build (145.9  manufacturing points - 100% social production, 0% military production). It does not take in account for the fact that the "Replication Center" replace the "Fertility Center" which costs 128 points (difference: 111 points).

Next actually queuing the "Replication Center" will show the proper 1 turn it takes to build.

 However the tool tip on the tile still shows the total cost (239).

For the actual building (upgrading) of the improvement the cost taken matches the cost/turns as shown in the "Manufacturing Queue" list.

To actually plan (and fine tune) your production: you need to known to cost of the improvement your are going to upgrade, calculate the difference and adjust your production to the calculated value. I find it hard to believe it is SD intention that the player should start to work with lookup documents / calculators just to know what that real costs are of an upgrade .

If this is a bug, please fix.

If this is by design, then i request a change to display the actual cost (aka the difference) instead of the total improvement cost.

While i am on the subject of the Manufacturing Queue:

Can the number of "turns to build" in the Manufacturing queue be updated when making changes (with any of the sliders) in the "Govern Planet" pop-up window?

When building a multi-turn improvement can there be a tool tip on the item in the "Manufacturing Queue" that shows either "points spend on building / cost of the improvement" or just the "number of points still needed to complete the improvement". And also show (or update) this in the tile tool tip .