Apple is able to block calls rigorously and perfectly, and does not display blocked calls in the call log. At no point do you find out when you receive a call that has been blocked by the device.
However, the Clever Dialer spam database also includes phone numbers that some users do not consider spam. This includes, for example, Sky, or some insurance companies. Apple offers no countermeasure possibility by means of an exception list (whitelist) on which such phone numbers could be deposited.
That’s why we’ve decided not to automatically block calls identified as spam and warn you from such calls. You can decide for yourself whether you want to accept the call or not.