Often a side-effect of the desire for fast feedback, because Fast feedback improves quality - but the mechanism by which we mock creates layers of indirection. This is so that we can utilise techniques like Single Responsibility, Interface Segregation and Dependency Inversion.
These layers of indirection, if they're not adding some domain-value through higher-order abstractions, are just introducing waste. It increases the cognitive overhead to understand the code and reason about its changes. It slows down feedback because of a tendency to overmock these relationships. As Overmocking creates alternative facts it is possible for test cases going through many layers of indirection to run through fictitious code paths that aren't representative of the production-like behaviour.
Fix by Test behaviour not implementation
Test-Induced Design Damage
Why Getter and Setter Methods are Evil
Indirection without abstraction is waste is an antipattern that occurs when objects introduce overhead through unnecessary layers of indirection
Mocks which are used internally at levels of indirection, if produced without abstraction can further damage the maintainability of production and test code, which is why Indirection without abstraction is waste
An observed effect is multiple layers of unnecessary indirection, and Indirection without abstraction is waste