When you log out, Claude Code asks Anthropic's server to revoke your sign-in token, meaning to cancel it so it can no longer be used. Before, any success reply counted as confirmation. Now a success reply that carries no Anthropic request id is not counted. Claude Code logs the message "OAuth token revoke answered 2xx without an Anthropic request id; not counted as acknowledged." instead.
The cancel request can also say which kind of token it is cancelling, and defaults to the refresh token as before. It now sends Claude Code's shared extra network options, and so does the request that creates an API key.
If you are behind a proxy, which is a go-between server that relays your traffic, the proxy may answer "success" itself without ever reaching Anthropic. Such a reply no longer counts as your token having been cancelled on the server.