Forum doesn't recognise existing Yubikey

Hi everyone,
my original username is ‘dinosm’. I had to make a new account to post, as the forum won’t recognise my Yubikey and won’t let me log in. I was careless enough not to have jotted down any backup codes.
Is there something that can be done, e.g. reset my 2FA for the forum by an admin, so that I can regain access to my original account?

I have tried with Firefox, Chrome and Edge. In every case, I get a “This security key doesn’t look familiar” error message. This is the only Yubikey I own, and it still works with every other website I use it with (including my own Nextcloud), so I am a bit sceptical about how this forum could have just ‘forgotten’ it.
Any help will be appreciated!

I can’t do this as moderator, I just see that your account has 2FA enabled. @admins