My original description (below) is wrong. The support page does work with Jira in 11.2 and 11.3. I have changed this ticket to fix an old link in a tooltip and to correct a formatting error for the username field.
The current FreeNAS support page is a form that submits tickets to Redmine via API calls. With our switch to Jira, the page is essentially broken. If Jira supports it, we need updated API calls(?) for support.fetch_categories, support.new_ticket, etc.