Earlier quoted context omitted.
> The new design collapses all responses below the second level I don't follow. I just opened a random comment thread, and counted comments being shown up to seven levels deep (which was the deepest comment.) Is the behavior you describe only if you're logged out or something?
I also don't follow. Here's a screenshot of the current top comment in the current top thread. It's showing 10 levels deep. https://imgur.com/a/itZrtRK
Try opening your link in an incognito browser.
If I go to the link posted above [1], I first see a much narrower window (careful, don't click on the black area to the sides, or you'll go back to the subreddit, the whole thing is basically a modal dialog now). Then I see one single comment, and it itself is half cut off. Below it I see a bunch of "related" content: https://imgur.com/a/tyaheDC
If I click the button to expand, I see no comments deeper than two deep: https://imgur.com/a/HDlNYFK
To see deeper any any thread, I have to click a link which doesn't expand the comments but takes me to its own link thread. To get back I need to use the browser back button and my context is lost.
They do not want users to engage with existing comments at all. The first comment is half cut off. The rest are hard to get to. They appear to want you to consume the posted content, and maybe post your own comment if you like.