Cannot sign in or authenticate with Mastodon account on mastodon.sdf.org

[Zachs-Kappler]

Been trying to use Twitodon off and on over the past few months but it keeps failing when signing in to my account with it. Tried signing in to the instance then signing in through Twitodon, and tried logging out and then trying to sign in through just Twitodon.

"Client authentication failed due to unknown client, no client authentication included, or unsupported authentication method."

My Mastodon instance is https://mastodon.sdf.org
Since this regards authentication, is there anything I can safely share beyond the error to help troubleshoot this?