The possibility to create an OpenPGP certificate for the keys on an OpenPGP smart card was added with T5125. We decided to remove it again because usually people will directly generate keys and a certificate with the "Generate new keys" function. Experts generating the keys on the OpenPGP card differently can use gpg to create an OpenPGP certificate.
Using this functionality to create an OpenPGP certificate for the card keys if there is already a corresponding OpenPGP certificate will cause chaos and confusion because both certificates will have the same fingerprint and Kleopatra will show only one of the two certificates (because they are internally indexed by the fingerprint). Similarly, gpg uses the fingerprint to uniquely identify certificates.