Decryption with smartcard keys are currently failing (tested: notepad, encrypt/decrypt workflow).
I created a new key on the smartcard (tested: brainpoolP256r1, nist256) and also ensured, that this is not related to stale smartcard/key data (tested: generation with no backup, restarted all gpg related processes) or other artifacts (tested: new clean gnupghome dir).
To reproduce e.g. in notepad:
1. Generate a key on smartcard (e.g. with default settings)
2. Encrypt some text in the notepad (encrypt for & sign with new key)
3. Decrypt again
audit log:
```
gpg: verschlüsselt mit brainpoolP256r1 Schlüssel, ID E2C4E1CFE5027094, erzeugt 2025-06-30
"sc"
gpg: Entschlüsselung mit Public-Key-Verfahren fehlgeschlagen: Ungültige Daten
gpg: Entschlüsselung fehlgeschlagen: Ungültige Daten
```
debugview output:
```
[8936] org.kde.pim.kleopatra: GpgME::DecryptionResult(
[8936] error: GpgME::Error(67108943 (Ungültige Daten))
[8936] fileName: <null>
[8936] unsupportedAlgorithm: <null>
[8936] isWrongKeyUsage: 0
[8936] isDeVs: 0
[8936] isBetaCompliance: 0
[8936] legacyCipherNoMDC: 0
[8936] symkeyAlgo: ?.?
[8936] recipients:
[8936] GpgME::DecryptionResult::Recipient(
[8936] keyID: 6F16E23204466286
[8936] shortKeyID: 04466286
[8936] publicKeyAlgorithm: ECDH
[8936] status: GpgME::Error(117440529 (Kein geheimer Schlüssel)))
[8936] )
[8936] GpgME::VerificationResult(
[8936] error: GpgME::Error(67108943 (Ungültige Daten))
[8936] fileName:
[8936] signatures:
[8936] )
```
gpgme log (decryption started 14:21:55)
{F25442272}
gpgsm log (nothing was logged on decryption though)
{F25442294}