Planet-level protective shields, a high-end product of shield technology, are also an important criterion for whether a civilization can reach the extragalactic colonization level. Being able to establish such a system indicates that the civilization has preliminarily mastered the technology needed to change an entire planet and create a primitive planet fortress. Don't assume that a planet-level shield is just larger than a warship shield. It's like the difference between heating by burning a pile of firewood and creating an air conditioner, two entirely different concepts. Implementing a shield for a spaceship and creating a planet shield are two completely different technologies. Initially in the Magic Prohibition World, to protect Earth, we had to use the Ghost Energy Field resonance of the entire Imperial Fleet's spaceships to barely establish a star shield, which shows how difficult this thing is to create.