Specifically when using Enhanced Default shaders, and with shadow resolution set to Very Low, gridlines show up on the landscape, especially when up-close. I could swear it happened with Low as well, but I cannot seem to replicate it again with that setting. The attached screenshot is using Very Low.
Edit: After testing settings more, I have realized it has to do with the Maximum Shadow Distance, the higher you have it, the more visible the gridlines are, to the point that they are visible even on Medium if you have it set to Way To Far.
Specifically when using Enhanced Default shaders, and with shadow resolution set to Very Low, gridlines show up on the landscape, especially when up-close. I could swear it happened with Low as well, but I cannot seem to replicate it again with that setting. The attached screenshot is using Very Low.
Edit: After testing settings more, I have realized it has to do with the Maximum Shadow Distance, the higher you have it, the more visible the gridlines are, to the point that they are visible even on Medium if you have it set to Way To Far.