Some things I think are objectively bad design -
1. Images open by default on my feed and videos and gifs autoplay as I scroll. It's a massive distraction. I'm trying to find content I might be interested in, but here I'm forced to scan pretty much every post out there.
2. On similar lines, showing a (cropped) summary for text posts. Again a distraction when you're trying to find content. The cropping makes it worse since you have to change the page after reading halfway through.
3. Having to click on view discussion to open the comments each time. This is a forum. The only reason I go there is to discuss.
4. Lack of borders for comments. It looks like one continuous feed and reduces grouping between individual comments.
5. Large avatars, icons on the reply bar compete for attention on every single comment. The reply bar on old reddit is so nicely blended away into the background. You don't see it unless you want to reply.
6. Hover popups on the large icons trigger unintentionally all the time. Very rarely do I need to see somebody's karma. What's the point of this feature even?
This is basis design considerations for a discussion forum. I completely understand where they are coming from though. They are not interested in this being a discussion forum. They want to optimize for post views. The more views a post gets, the more they will be able to monetize. Engaging in discussion is time consuming and that time could be better spent in viewing more posts.