The application probably doesn't support this curve, the changelog only mentions Curve25519 and NIST P-256. Also Kleopatra lists only these two curves when generating a key from the card. Upon further inspection, the 0xFA DO listing the supported algorithms only has RSA 2048, RSA 4096, nistp256, ed255519 and cv25519

This is a Nitrokey 3A with the firmware 1.2.2-alpha.20221130. I'll check with the vendor.

Changing the key attributes didn't help unfortunately:

I also tried to import the key with the gpg-card writekey command and I got the same error.

Same error message but probably a different cause, in this case the card was factory reset before importing.