When the 'Particle Effect' Window is shrunk vertically so that Scene Gizmo came exactly parallel then On clicking Stop Button from Particle Effects Window resulting Scene Gizmo 'Perspective' mode and 'Orthographic' mode is selected, Refer to attached video.

Steps to repro:
1. Create a New Project
2. Hierarchy > Effects > Particle System
3. Shrink Scene Window vertically such a way that Particle Effect window present on Scene Gizmo.
4. Particle Effects > Click on Stop Button.

Actual Result:
Scene Gizmo is selected through the Stop button of the 'Particle Effect' Window.

Expected Result:
Scene Gizmo should not be selected when clicked on the Stop button of the Particle Effect Window.

Reproducible in:
2021.2.0a6, 2021.1.0b8, 2021.1.0a3

Working Fine in:
2021.1.0a2, 2020.2.6f1, 2019.4.21f1 .

Environment:
Occurring on Windows 10 & macOS 10.15.