In Prefab Variant clicking the "Open Prefab Assets" arrow editor thrown Multiple errors, Refer to the attached video

Steps to repro:
1. Create a new Project.
2. Hierarchy > Right-Click > 3D Object > Cube
3. Create Prefab and Prefab Variant
4. Add Prefab Variant in Hierarchy
5. Hierarchy > Cube Variant > Click the "Open Prefab Assets" arrow

Actual result: Multiple errors are thrown opening Prefab Variant from the Hierarchy

Expected result: No error in the console

Reproducible in:
2021.2.a16

Working Fine in:
2021.2.a15, 2021.1.6f1

Environment:
Windows10 and Ubuntu 18.04 LTS

Stack trace:
State comes from an incompatible keyword space
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)
Incompatible keyword states
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)