How to reproduce:
1. Open the attached project
2. Open SampleScene
3. Select MyCustomTexture in the project window
4. Right-click in the inspector header > "Apply Texture Change"
5. Note that the color of the Sub Asset texture changes
6. Right-click again > "Apply Texture Changes"
7. Note color changes again

Expected result: The color of the Sub Asset does not change
Actual result: The color of the Sub Asset changes with each click of "Apply Texture Change"

Reproducible with: 2020.1.0a18, 2020.1.17f1, 2020.2.3f1, 2021.1.0b5, 2021.2.0a4
Not reproducible with: 2018.4.30f1, 2019.4.19f1, 2020.1.0a17

Workaround: Call Resize with GraphicsFormat.R8G8B8_UNORM instead of the texture format