False positive "keyboard-interactive" / "Further authentication required" from Multi-Factor

After following the “How To Set Up Multi-Factor Authentication for SSH” guide (https://www.digitalocean.com/community/tutorials/how-to-set-up-multi-factor-authentication-for-ssh-on-ubuntu-20-04), all users get the Further authentication required / keyboard-interactive message from the server when logging in - also users that doesn’t have multi-factor active.

This messes with the PHP library I use to make SSH connections, phpseclib, as it expects to be prompted for multi-factor, but it actually doesn’t.

Connecting through something like PuTTY, it works just fine; it does note that “Further authentication is required”, but it just ignores it and successfully logs in - I’m just not that lucky with the mentioned library.

I did follow Step 7 in the mentioned guide, but it still seems like it prompts somehow…

Does anyone know how to make the server not send the keyboard-interactive message to the client, when it’s indeed not needed?