We're converting over to New Experience in my organization and one thing that was called out to me was that the updates page for tasks and issues no longer shows the reference number. In the Classic UI, it was on the right side of the screen in the "box" with all the other information that has now migrated to the header (assignee, due date, status, etc.), Our organization is very ticket#-focused and while not having this on the update page doesn't break functionality for us, it does create a couple extra clicks to find the information in the details page.
