This is a complicated aerodynamic principle. For example, if you cut an apple with a knife, when you cut it halfway, both sides of the knife will be squeezed inward by the apple. In the absence of external force, the squeezing force of the apple is equal, which will force your knife to move straight in the tangential direction to prevent it from being crooked.

The missile tail is like a knife, the air is an apple, and the missile tail is a four-sided cross. When cutting air, it will be subjected to space extrusion pressure from eight directions, which will play a role in stabilizing flight according to the balance of forces.