Forge v14.23.4.2707-1.12.2
Dynamic Trees v0.7.8
Project Wish v0.0.7
When the stick block (ID is wish:stick@0) from Project Wish spawns next to the root block during world gen, this happens:

If this needs to be reported to the Project Wish mod instead, then I can do that.

This happens because of the mimic property of rooty dirt. It will emulate the appearance of adjacent blocks whose material is Material.GRASS or Material.GROUND and then overlay a root texture over the model. This was done to meet the impossible variety of modded dirt blocks out there.
The "wish:stick" is a block of which the material type is Material.GRASS. This doesn't seem like the appropriate material for sticks to me but maybe there's a reason for it that unaware of.

Fixed in dev. We'll only mimic blocks that are normal cubes.

OK, thanks