This issue is too old. We don't have the capacity to check if it still happen. If you still observe it on recent version of Unity, please re-open. Thanks
Reproduction steps:
1. Open the attached “Testbed 2021.zip“ project
2. Open “DepthNormals” scene
3. Enter Play mode
4. Observe the Editor
Expected result: Render is visible in the Game window
Actual result: Render is visible in several different windows of the Editor