There are perspectives to consider here.

Among the classes that implement the interface, there is greater coupling, but not as strong. This coupling is even stronger in versions prior to Java 8, in which classes that implement these features MUST be recompiled if any new functionality is added to the interface. Although classes must implement the functionality themselves, there is no dependency on the implementation of the functionality, just a set of functionalities to be implemented.

For those who use it, reusing the interface's functionalities through polymorphism is very good coupling and requires no modification.

And from the interface's perspective, there is a larger set of possible classes that can use the interface.