When playing an explored Black Forest Map with AI and building the market you get a texture of placeholder presumably for the enemy TC that is not yet discovered.
Interesting. That’s the old snowy road texture which isn’t used anymore.
(The game now layers snow on top of the dirt road, except in this case apparently)
Just look to the right on your screenshots at the snowy road. There is in fact no texture in the game files that looks like that.
If you go into the scenario editor, place down the road-dirt and then click the layering mode button, you can cover it in snow and make it look like that.