Texture import carves streaks along X axis

v2.8.1 using Unity 2021.2.2f1 (also tested in Unity 2020.3)

1. New scene
2. Add import node with Clamp wrap mode
3. In Matrix Asset properties, select Texture, use Grayscale channel
4. Hook up to Height node in graph
5. Observe no lines along the X axis
6. Offset Import node on X by 500
7. Observe line(s) along the X axis

You can see an example of this bug in the documentation itself for the Offset property of the Import node.

In this case, "lines" refers to strips of white or black in the heightmap, which results to either impressions (a map-wide trench) and/or perfectly raised line(s).

Repro is not 100% and results may vary. For some it's a single line, others it's multiple large lines (also along the X axis).