So. While checking the roads at Pixel Gate I noticed some weird pattern. @SilberB reminded me of it. And my perfectionist side wanted to find out.
So there seems to be a problem with blocks merging different ways depending on the planet resources come from. Don't know if it's a feature or it was just overlooked.
Further looking into it. With the different bricks I had, I noticed that depending on how you placed the blocks, they would merge or not merge. Except the ones from Epsilo.
Haven't tried any other planet, than the ones mentioned.
There also seems to be a nice interaction with slabs, where they kind of half merge or not merge at all, not even a little color onto other blocks. I tried different bricks against different timbers this time. And it seems the Solum timber offers the best not merging results.