The sink closure captures d2, a locally scoped variable, but has no reference to any variable or method on self, hence self is not captured.

class CombineTest {
    let d1 = Deinit(1)
    let subject = CurrentValueSubject<Int, Never>(0)
    var cancellable: Cancellable?
    func subscribe() {
        let d2 = Deinit(2)
        cancellable = subject
            .sink { value in
                print("\(value) \(d2.n)")
            }
    }
    ...
}

This is further reinforced by the fact that d1 is shown to release and deinit when CombineTest is released, which it would not do if there was a retain cycle on CombineTest.