Keybase on iPhone asking if I have (the same) iPhone handy on login

I have only occasionally used Keybase since setting up my account.

Logging in to the iOS app on my iPhone yesterday, I was prompted to "prove you're you". The only option I have for "other devices [that I] have handy" is the very iPhone on which I am trying to login. I attempted this just in case, but it did not work. On the other hand, I could reset my account but I really would prefer not to do that until I confirm what's going on.

I do not think that I have uninstalled Keybase or made other relevant changes to my account. Reviewing the "added" date for this device, I'm not forgetting a device upgrade. so I'm not sure why I am being asked to prove my identity, nor how I could possibly do so under the circumstances. Is this possibly a bug, or are iOS clients deauthorized under certain circumstances (certain OS upgrades, suspicious interactions, etc.)?

Start by reproducing the Keybase iOS login flow described in the issue, focusing on the "prove you're you" prompt and its available devices. Investigate why the current iPhone is offered as the only other device and determine what behavior or recovery path should be considered done.

Written by the indexing model from the issue text.