Could you explain what exactly you are expecting it to do that it doesn't do?

In general neither the API nor anything else on the server has any concept of something being closed as we don't have an area type. Some editors may treat lines which start and end with the same point specially and apparently you would like the browser view on the web site to do so, but you haven't said what it is you would like it to do.

He means, the list has the node as a member of the same way referenced two times: 3984033658 (member of ways 395560549 и 395560549). It should be a set, not a list.

It can be argued that the duplicate mention of the (same) way is language wise an error in any case. Maybe a simple language change is enough to make it cleaner.

Old example is buried somewhere in way history, new example: https://www.openstreetmap.org/way/4683291

Way 38816094 is shown twice for node 29761716