I'm using age keys but sops seems to fail if my ssh key (with passphrase) exists

[a-torgovitsky]

sops ./secrets/shared.yaml
Failed to get the data key required to decrypt the SOPS file.

Group 0: FAILED
  age1g4j57xuwyaqykdfc6uvt78fmnnpk3yjehmskg02wpupkly4sdyfszq3099: FAILED
    - | failed to load age identities: failed to get SSH identity:
      | malformed SSH identity in "/home/at/.ssh/id_ed25519": ssh:
      | parse error in message type 0

  age1nrkt44w2dgwkff85thy6fyucx6g60smpezaltvl8d5dxn8g4yvrse04fpj: FAILED
    - | failed to load age identities: failed to get SSH identity:
      | malformed SSH identity in "/home/at/.ssh/id_ed25519": ssh:
      | parse error in message type 0

Recovery failed because no master key was able to decrypt the file. In
order for SOPS to recover the file, at least one key has to be successful,
but none were.

The shared.yaml file was encrypted with ~/.config/sops/age/keys.txt.
There is a .sops.yaml located in . that has the public key in keys.txt (as well as a different public key for a different machine).

My id_ed25519 SSH key has a passphrase, which is why I suspect I am getting the message that sops thinks it is malformed.
However, I would have expected sops to just skip the SSH key and go on to find ~/.config/sops/age/keys.txt.
If I rename the id_ed25519 SSH key, then sops works as expected, decrypting and opening the shared.yaml file.

What am I doing wrong?