@romullus Yeah, that is a good question. tldr; gamma correction
The normal map is being imported with a gamma override (1.0) and then a 0.45 gamma correction is being applied in the color correct texmap.
Technically, the normal map could be imported with an automatic (recommended) 2.2 gamma correction, and then the color correct texmap would not be necessary, but I'm so accustomed to applying gamma override (1.0) to normal maps on import, I didn't want to adjust the import settings for this one map.
The normal map was baked out from a .SBSAR in the Slate Material Editor and I think a gamma curve is being applied internally during that operation(?) I've been talking to the integrations team about it to get some clarification.