Why is divergence at the level of microevolution is reversible, but at the level of macroevolution is it irreversible?

Because the genetic changes that occur at this level (microevolution) are relatively simple and their direction can easily change. Irreversibility becomes a feature of evolution at the levels of speciation and macroevolution.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.