How to reproduce:
1. Open attached project "ScreenshotBugStripped.zip" and scene "SampleScene"
2. Enter Play mode
3. In Game View, set Custom Resolution to 3000x3000 pixels
4. Press 'Space' bar key
5. Observe Console window
Expected result: "No Error" is printed
Actual result: "CaptureScreenshotAsTexture" failed is printed
Reproducible with: 2018.4.26f1, 2019.4.6f1, 2020.1.0f1, 2020.2.0a18