Rarity

Even if you're running a Starfinder campaign with no Pathfinder elements, or vice versa, use the uncommon and rare traits to highlight that not every published rule element is appropriate for every game. A good rule of thumb is to assume everything that exists only in Starfinder is uncommon in Pathfinder, and vice versa. Rules elements that rely on ancestries, classes, deities, or equipment should be assumed rare, and you should analyze them carefully to make sure they fit your campaign's themes before allowing players to choose those options.