Connected Services - 'Unknown' device that I cannot 'Sign out' of

[tgeesaman]

Description

I received a notification last night that an 'unknown' device had signed into my Mozilla account. I signed into the accounts.firefox.com/settings#delete-account website and noticed an 'unknown' device under "Connected Services". There is a "Sign out" button but clicking it doesn't do anything. I was able to sign out of other connected devices so I'm not sure what the issue is.

Steps to reproduce

1. Sign into Firefox via web and go to Connected Services section
2. See "unknown" device and click "sign out"
3. Nothing happens

Expected result

Sign out of unknown device to stop security breach

Actual result

Nothing happens

Environment

Attempted on Apple iPhone via Safari and Windows 11 via FireFox

┆Issue is synchronized with this Jira Task

[tgeesaman]

It is worth noting this is not an isolated issue it appears:

https://www.reddit.com/r/firefox/comments/1hprwm7/unknown_signed_into_my_mozilla_account/

https://www.reddit.com/r/firefox/comments/1hp058j/erroneous_login_at_4am_from_unknown_device_that_i/