I don't really follow why this->guard()->user() doesn't work here (maybe because this is called with the refresh token instead of the user token?), and retrieving it via event listener does look surpristing, so a clarifying comment might help:

e.g. The token refresh is using a refresh token instead of an access toke, in which case this->guard()->user() doesn't work. We listen for the newly refreshed token, so we can resolve the user that is then used to directly return user-info in this request.