Hello 
I think this is relevant: Clicking on links in posts and go back makes incorrect post height
I think now I found a pattern for this bug. This is what I am thinking and it’s not sure this is happening. 
When you go back it keeps the previous topic next post(s) height (I think we can only see it visually if it is taller)… 
Let me clarify what I am thinking.
I opened two topic to demo it.
I go from the first topic to the second topic and back. What happened? The first topic post’s are taller as I show it on the video here Clicking on links in posts and go back makes incorrect post height
Now I check the posts in first topic. Here is one.
It gets a calculated min-height.
As I see this value calculation is find here and use the post-id attribute
So let’s check the post-ids and see what’s happened.
In the first topic post the post-id is 12.
In the second topic we have to find the post-id 13 post. Which is this.
This seems the post content height adds the empty space to the first topic 12th post.
As I see this is only happens if I use the slider loader. I am not sure what’s happening (but maybe because the loader slider is keeps page open while go back to the previous page) and starts the min-height calculation on the second topic and when I go back to first topic this calculation added to the actual posts height.