All our customers can have a service desk customer account which they need to ask support. If a customer uses this service desk to e.g. request a feature, we might log this as a feature request in our "public" jira (a jira project where anyone can view the issues and see their progress). Typically, the service desk ticket is then closed with a message that a feature request is made (with a link to it) and that we plan to deliver this feature then or then.
An anonymous user can - like expected - view the ticket. If that user then clicks on login, he can login using his service desk customer login, and can still see the ticket and navigate the public jira project. However, once he visits the service desk portal, he cannot return to the public jira project anymore, as he keeps being redirected to the service desk interface.
However, we want all users (anonymous and service desk customers) to view and browse our public jira project.