Steps to repro:

1. Open the attached project and 'SampleScene' scene;
2. Make sure that you have 2 active scene views in the Editor layout, if not, add the second one and attach it to the active Editor window;
3. In the Lighting window press "Generate Lighting" button;
4. When the baking is finished, click on one of the Scene view tabs;
5. Set the Lighting Exposure' slider value to -10.

Expected result:
The lighting exposure is changed only for the active Scene view instance.

Actual result:
The lighting exposure is changed for all the active Scene view instances. See attached video.

Notes:
- Reproducible in 2020.1.0a5, 2019.3.0f2;
- The issue was introcuced with the lighting exposure slider that was added in 2019.3;
- Reproducible on Windows 10;
- Toggling lighting exposure behaviour is different when inputting value in the text field and when changing the slider position: in the first case the exposure changes instantly for all the scene views, in the latter it only changes the exposure of the active scene view (expected), however, when the mouse is hovered on another scene view, the exposure of the scene view that's been hovered on is incorrectly rewritten with the changed value for the initially changed scene view.