Issues Creating Push Mirror to GitHub

Hello,

I’m having an issue creating a push mirror to github from gitlab.com. I’ve generated a new ssh key (ecdsa) for this which I added as a deploy key with write access in github. When I try to use this key as the host key for the mirror it fails to sync with the following error:

13:get remote references: create git ls-remote: exit status 128, stderr: “No ECDSA host key is known for github.com and you have requested strict checking.\r\nHost key verification failed.\r\nfatal: Could not read from remote repository.\n\nPlease make sure you have the correct access rights\nand the repository exists.\n”.

On a local system this would seem like I need to update a known_hosts file, but I have no idea what this would mean in this context.

I have noticed a couple of oddities:

  1. I still get the above ECDSA specific error even if I use an RSA key
  2. The public key that I get from clicking the “Copy SSH public key” button is not the same one I provided and in fact looks like an RSA instead of the ECDSA

Thanks in advance for any help you can provide!

Same issue, despite I’ve filled the github keys manually from they page (GitHub's SSH key fingerprints - GitHub Docs)

Any clue?

Guess it’s not supposed to work either - official documentation (Push mirroring | GitLab) says to use insecure PAT for sync with GitHub, it’s a very unpleasant issue, of course