As of June 29th, 2020, Enterprise releases are now called Long Term Support releases. The security bug fix policy for these releases was also updated - we will continue to backport critical security bug fixes and now when architecturally possible, all other security bug fixes are backported to the release for 24 months. To learn more about this change, view our Community post.
Here is the announcement blog post: https://www.atlassian.com/blog/enterprise/the-new-jira-enterprise-releases-are-here?utm_source=&utm_medium=community&utm_campaign=cops_fy20_q2__jira-software_8-5-er__blog___enterprisegroup&_ga=2.50494377.1251945153.1571763268-1138330856.1568759638
Release notes for JIRA Software 8.5: https://confluence.atlassian.com/jirasoftware/jira-software-release-notes-776821069.html
Release notes for JIRA Service Desk 4.5: https://confluence.atlassian.com/servicedesk/jira-service-desk-4-5-x-release-notes-975042134.html