Problem with ddy and ddx in shader in combination with Nanite

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I believe the reason for this is explained in this talk https://www.unrealengine.com/en-US/blog/take-a-deep-dive-into-nanite-gpu-driven-materials The relevant section is page 23 of the PDF. Essentially, it has to do with mipmapping and nanites manner of merging material rendering into a single full screen pass. Messing around with a nanite mesh’s UVs can interfere with the way nanite addresses this, causing a UV seam in manners that may not have been a problem with non-nanite meshes. You may…