I have the same issue. No matter what number I choose (i.e. whether it's a contact or an unknown number), its card looks like the above.
I had to write down the number, then go to the Settings app and manually add it to the blocked list.
WTF? I know Apple couldn't care less about spam, seeing that even after 18 years it still obstinately refuses to give us proper anti-spam tools. But to cripple even the little that we already had is really unbelievable. 🙄