When the uv value is very close to 0 ( < 0.001 ), the boundary value of the PVRTC texture is sampled as white. please refer to attached images and sample project.

problem goes away when changing the texture format to ASTC 

Steps to Reproduce
  1. unzip attached sample project
  2. open project with UE 4.27.1 on Mac
  3. select IOS provision and certificate
  4. package for IOS development
  5. deploy to any IOS device

expected : Shading color on IOS device should be same as IOS preview on Editor

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Won't Fix
ComponentUE - Platform - Mobile
Affects Versions4.
Target Fix5.0
CreatedOct 20, 2021
ResolvedOct 29, 2021
UpdatedOct 29, 2021