Changes done on Scripts Icon with UNDO action appear back

Changes done on Scripts Icon with UNDO action, appear back in the inspector window, on editing the script in the script editor, and returning back to the editor.

Steps to repro:
1. Create a new project
2. Project window > Create > C# Script
3. NewBehaviourScript > Inspector > Select Icon > change Icon (e.g. Blue)
4.Edit > Undo > Undo Set Icon on GameObject
5.Observe scripts icon in inspector window changes back to default
6. Open the same script > make some changes > save > return back to the editor
7.Observe the script's icon in inspector window again changes back to (Blue) the icon set in step 3

Actual Result: Changes done on Scripts Icon with UNDO action appear back

Expected Result: Changes done on Scripts Icon with UNDO action should not appear back

Occurring on: 2021.2.0a15, 2021.1.5f1, 2020.3.6f1, 2019.4.25f1, 2018.4.34f1

Environment: Occurring on macOS and Windows 10