What will happen in an ecosystem with a strong decrease or increase in the number of individuals

What will happen in an ecosystem with a strong decrease or increase in the number of individuals at one link in the food chain?

If we assume that we are talking about such an ecosystem as the savanna, where, for example, the number of herbivores has increased, then the growth of predators will soon increase, as well as the amount of grass will decrease, and by the next season their number will equalize. If there are fewer herbivores, then the number of predators will decrease, and the amount of grass will increase, which will give the herbivore the following advantages: they will be hunted less, they will have more food. In this regard, their number will increase, and then, accordingly, the number of predators will also increase.