Post Block

Hello, I have a question about the post block page. It used to work fine but recently I’ve noticed that the two first posts on top are horizontal from one another while all of the others are lined up vertical to the right with only one post on the left. I know this sounds confusing but here’s a link to the web site page: https://ai.dorianlatelle.com/stories/

Also (this is very important) I’m wondering if there’s anyway to exclude certain posts from showing on the post block page? Thanks!