When a transparent material has "Allow Custom Depth Writes" enabled it is prone to have artifacts in the custom depth buffer under specific conditions.
The conditions are as follows:
An interesting thing is that the artifacts wont appear if you don't use a texture sampler with depth fade in some way. In my test project I subtract the texture sampler RGB values from depth fade. If you use a 3 vector you won't get the issue even if it is the same value as the texture. To prove this I used a plain white texture and then swapped it out with a 3 vector of (1,1,1).
The floor mesh's material is outputting noisy artifacts to the depth buffer. The noise appears to resemble values from the texture applied in the terrains material.
The floor mesh appears light grey in the visualizer.
Head over to the existing Questions & Answers thread and let us know what's up.