Can't get ssh to work with key pair

hi there.

i can’t seem to get SSH authentication to work! maybe i’m making some mistake in my config, but when i remote in it just says

root@[redacted]: Permission denied (publickey,keyboard-interactive)

the config for the ssh/terminal add-on is this:

authorized_keys:
  - '!secret pop-os-ssh'
password: ''
apks: []
server:
  tcp_forwarding: false

and the key is in my secret file, it looks like this (obviously key redacted)

# Use this file to store secrets like usernames and passwords.
# Learn more at https://www.home-assistant.io/docs/configuration/secrets/

###############################
# SSH keys for remote access: #
###############################

# Public SSH key from Pop-OS:
pop-os-ssh: [redacted]

Is there something i’m doing wrong? i followed this guide for key generation (like it says in the doc):

and how can i debug whether SSH is actually giving the proper key?