As you can see in the 2 images below, the Trees are placed in a perfect grid. I started this Map in 0.17.xx and loaded it in 0.18.40 but i don't know if it was like this back then. Now in 0.18.42 this catched my attention.
I've attached the Save file. I used the Mod Biters Begone so i could have a closer look without bombing it away.