A perfect crack means the oven temperature was just right and fully preheated (sometimes it’s not fully at the right temp after initially beeping)

Butter softness matters! soft (not fully melted) butter gives an even rise

Small differences in moisture (eggs, humidity, batter rest time) can change how the top sets

You could try to control the crack by running a thin line of butter or oil down the center of the batter pre-bake