Great job, Sergey and team!
Suggestion: Using the accordian feature in an item page, when you open one accordian (tab), it closes the previous one that was open. Just keep them all open/extended and allow user to manually close, as needed.
Feedback: Using both the new accordian and tab features on the item page, I prefer the tab ... as it closely mirrors the fields as they appear on the form page. (However, the new form "row" feature is not available on the item page).