How to reproduce:
1. Open the user's attached project
2. Open 'SampleScene'
3. In the Hierarchy select 'Gradient'
4. In the Inspector click on the 'Copy' button
5. Click on the Grad field
6. Change the color of the gradient in the Gradient Editor window
7. In the Inspector click on the 'Paste' button
8. Observe the Grad field

Expected result: The Grad field is red
Actual result: The Grad field is the color that was set in the Gradient Editor

Reproducible with: 2018.4.31f1, 2019.4.20f1, 2020.2.3f1, 2021.1.0b5, 2021.2.0a3

Notes:
- The preview is updated after opening another app or clicking on the Grad field