I believe that would impact biodiversity in the way that, all those preys the predator feeds on, will start to overpopulate.
Like for example, I’ll use a wolf. Wolves eat many other animals, so it would be a top predator in an ecosystem. But when the population of wolves start to drop, their prey’s population will increase. This isn’t necessarily a positive thing because there has to be a balance in the food chain.
Wolves probably also do something for the environment, so a decrease would maybe change somethings there too.
I hope this answers your question :)