How to reproduce:
1. Open the attached project's Scene labeled "BugReproductionScene"
2. In Quality settings, set the Texture Quality to "Half Res"
3. Enter the Play Mode
4. Inspect the "ReproduceBugQuad" GameObject's Texture

Expected result: Texture's pattern fills the Quad completely
Actual result: Texture's pattern only fills a quarter of the Quad

Reproducible with: 2019.3.0b12, 2019.3.0f6, 2020.1.0a21
Not reproducible with: 2017.4.36f1, 2018.4.16f1, 2019.2.19f1, 2019.3.0b11

Note: Other Graphics.CopyTexture overloads work fine and gives the expected results