Suggestion: On the colony manager screen, the one which lists all of your colonies, where colony population is shown, also show the potential max population based on current food production.

That is, I know a planet is at 10 billion people. I can see the approval is at 90%. I cannot see if the planet is at max pop now, meaning I can plunk down another farm without approval dropping through the floor.

If there is no room for a max population field (there should be), then instead colour code the population field based on Growing, Decreasing, Maxed, ... (perhaps "Stuck" too, based on approval on planet being too low to create growth).

Green for Growing.
Red for Decreasing.
Bold green for Maxed.
Bold red for Stuck.

Good job on the UI improvements thus far. It is all about cognitive load and the appropriate type of feedback to the user in response to their actions.