This problem may have been around since the release of entrenchment but recently in the full release of Diplomacy I noticed that as the Advent if my planet has a starbase upgraded with the tech "enduring devotion" the pirate siege ships will never stop bombarding the planet even though the starbase is actually preserving my control of the planet. The AI of pirate siege ships needs to be fixed to target starbases after the planet's health and population reach 0 because currently the AI is set to bombard until player loses planet. I've heard that pirates have been given anti-structure attack also in this release so it's sad that they don't in this scenario turn around to waste my friends starbase. With the ability to give pirates missions in this game now, it's even more important to fix this in the next patch. (By the way, I love having the pirates stronger in diplomacy. People can now, for one new strategy, focus on economy and send a pirate force of 1000 fleet supply  to attack enemies)