Confused about expiration and how to update them

I just realized my keybase key is expiring in a month. I tried to update the expiration normally trough gpg, but I stumbled when it asked for my passphrase, since I don't remember setting one (I remember letting keybase have that secret key), I don't know what to do.

I can unlock it normally, signing and encrypting files also without any issue (and using the keybase passphrase for that matter), so I'm guessing the secret key is really on the server?

I see some issues around expiring keys, but they all say "update it through gpg".

The issue mentions GPG key expiration, the Keybase passphrase, and the possibility that the secret key is stored on the server, but it names no repository files or tests. Start by reviewing the existing guidance for expiring keys and the GPG/key-unlocking flow; done means documenting how users update expiration and which passphrase or key location applies.

Written by the indexing model from the issue text.