As a sibling commenter said, I think the background texture is the most distracting.
Other than that, I also think the tag density is higher than on Lobsters, where they seem to be using mostly one, or at most two, tags, whereas this website's front-page is using around three for each post.
Maybe the color scheme as well. And perhaps more negative space can be removed by making the column wider, like it is on HN.
They've also gone with the sadly-ubiquitous "tiny fixed width column of content with heaps of whitespace on either side" pattern. Real HN does have whitespace borders after a certain width, but it mostly allows the content to scale to fit your browser window. Nothing worse than having a nice gigantic monitor and then having web content constrained to a 5" vertical strip down the middle of it.
For me, it's the fact that the tags overflow to the next line on mobile. Some posts only have tags on the right, some only have tags on the next line, some have both.
The inconsistency makes it impossible for my eyes to settle into a reading pattern.
As a gamer though I immediately noticed how easy it was to visually filter the content by tags and drill down into the details at will. It's an uncommon texture but it works for me.
Other than that, I also think the tag density is higher than on Lobsters, where they seem to be using mostly one, or at most two, tags, whereas this website's front-page is using around three for each post.
Maybe the color scheme as well. And perhaps more negative space can be removed by making the column wider, like it is on HN.