OpenSSH signatures in general contain signer's public key, which I personally think it's not weird but rather cool since it allows verifying the signature without out of the band key delivery (like in OpenPGP). The authentication of the public key is a separate subject but at least some basic checks can be done with an OpenSSH signature only.
hope you do key selection sanitization instead of the default (nobody does). otherwise you're accepting random keys you have laying around (like github) when logging to secret.example.com
This information could be used by SSH servers you are connecting to. You might think you are connecting anonymously, while in fact your SSH client is sending your public key which could then be resolved to your GitHub account.
add one Host entry per domain.
on the end of the file add one catch all host rule with IdentityFile /dev/null
otherwise you're sending default key names to all hosts.
...and you are not sending id_rsa.pub to every single place you add a key, like most guides suggests, right? right?
guides dumbing down things are the root of evil.