mm_answer_keyallowed: publickey authentication test: ED25519 key is not allowed

Debian 12.
After a long time I’ve installed Debian 12 in a VM again.
I used ssh-copy-id to copy the key files to the VM.
When I tried logging in, I still had to supply my password.
What was going on?

Well, I’ll spare you the mindfuck and give you the solution.

It wasn’t the encoding, it weren’t the permissions, it was…
My .ssh/id_ed25519 and .pub were dated older, from 2021, than a newer key I generated for github, id_ed25519_github.
So, I don’t know why all of a sudden this is happeneing, ssh-copy-id decides to take the most newly generated key in the .ssh directory, which is the github one and ignore all other keys.

In order to fix this

because ssh-copy-id since, who knows when, takes only 1 ed25519 key and it’s always the latest one.

I usually always did the copy/pasting by hand, until I stumbled on some smarty-pants blog-post which suggested ssh-copy-id. I’m going to fall back to doing it manually again.