The nature mentioned in the question is balanced, which usually means that the natural system is a stable circulatory system. The so-called defect and balance are not in the opposite sense, and defect does not mean imbalance. Only when the defect reaches a certain level and destroys the stability of the system can the balance be defined as being destroyed.
Judging from its own development and present situation, nature is a stable development system with strong tolerance and automatic error correction ability, so it is debatable to say that nature has defects. We can't prove that nature is flawed just because everything has weaknesses, which is one-sided. For example, the short life span of microorganisms, we can say that this is the weakness of microorganisms, but this weakness is precisely the necessary link of material decomposition and the key to maintaining the stability of natural systems in nature.
It is a false proposition that people do not feel imbalance. Balance is not based on human feelings, it is objective. People can scientifically judge the balance of a system through perceptual cognition and rational cognition, but it is unreliable to rely solely on feelings.
Finally, the balance of the natural system is indeed being broken, and industrial civilization has caused a heavy burden on the natural balance system, and even faces the danger of system collapse. People can feel this, and the most intuitive feeling is that our quality of life is getting worse and worse, and the right to enjoy fresh air and clean water is being deprived little by little. When the stability of a system can be intuitively felt, it has often reached the final stage of stability, which is very dangerous.