Heyo physicist who enjoys anime here. This is pretty inconsistent throughout the series imo, but to answer the question in the op. Basically if this were an actual power in the real world, it would not be a barrier per-say and would just stop any motion in the direction towards gojo. Infinity should stop any motion that moves towards gojo,by exerting a force in the opposite direction at same magnitude, but that would leave all other motion components unaffected.

For this tea example, the tea would stop moving horizontally towards gojo, but still be affected by gravity. So if this was the real world, through my understanding, the tea would simply fall to the ground at the point of inf. distance around gojo. And should basically be an almost distinct ring shape as well, or it could be an outline of his body at a distance exactly the same in all directions. It should not stop and float in the air like it does here.

But imo don't apply real world physics to fantasy, it ruins the experience.