I found out how to correct this, go to this link How to fix terrain shader issue - Twitch. The path for you game files might be in a different location if installed in a different location. Easy way to find it, is to open up steam select the game (farming simulator25) right a crossed from Play is a gear icon click on that. Then click on manage>manage local files. File explorer will open then data folder>shaders folder. Then follow video from there. The terrainShader.xml files must be partially corrupted.