There are planetary improvements that the player can build that effect every planet in their civilization, or similarly effect their entire civilization as a whole. There are also planetary improvements the player can build that effect only that specific planet. In many cases there is nothing in that build projects description that specifies which kind of effect it has (single planet or empire wide). One specific example is the "Virtual World" building; it gives a +3% approval bonus to every citizen in your entire civilization (which is a big deal), but nothing in the pop-up description tells you if it is empire wide or specific to just that planet.
Please make it very clear when a planetary building project has civilization wide effects, as opposed to just a single planet effect. This is especially important for newer players that might not realize they are missing out on huge civilization wide bonuses.
Happy Bug Squashing !